user14288: It seems to me that according to one interpretation of the "3rd precept" of the 5 precepts one could even engage in various sexual acts with a vast number of prostitutes nonstop and that still wouldn't be considered as breaking the "3rd precept". (I am doubtful of it being possible to attain stream-entry with that indulgent behavior therefore I believe the Buddha did not teach that as being a way to attain stream-entry.) 
Why has the "3rd precept" of the 5 precepts been interpreted as being so permissive?
I find it concerning how the "3rd precept" of the 5 precepts has been interpreted as being so permissive. 

user295: Engaging in sex with someone who is not under another's protection or care does not break the precept. There can be prostitutes who may not fall into this category who are under their family's care but doing this on the sly. In this case, the 3rd precept may be broken. Also, there may be non-prostitutes who are not under protection. E.g. in western culture when one becomes independent and moves on to one shelter perhaps it can be thought of as been not under another's protection and care if they are totally not under the care or concern their parents and relatives. Therefore, sex in this context does not break the precepts.
To have sex one must develop sensory desire (kāmacchanda) which is one of the 5 hindrances. This effective barrier to stream-entry. Though you are not breaking the precept, one is creating a barrier for its realisation.

user8157: I have explained the original Buddhist teachings about sexual conduct & misconduct, before. 
The 3rd precept in the Pali suttas (e.g. AN 10.176) says a daughter is to be "protected" by her family. 

Abandoning sensual misconduct, he abstains from sensual misconduct. He
  does not get sexually involved with those who are protected by their
  mothers, their fathers, their brothers, their sisters, their
  relatives, or their Dhamma; those with husbands, those who entail
  punishments, or even those crowned with flowers by another man.
AN 10.176

Per the later Commentary, the word "protected" means, per the DN 31 sutta, the daughter is "restrained from unskillful behaviour" until the "parents arrange a suitable marriage" for her into a good family. 

In five ways, young householder, a child should minister to his
  parents as the East:
(i) Having supported me I shall support them,
(ii) I shall do their duties, 
(iii) I shall keep the family tradition, 
(iv) I shall make > myself worthy of my inheritance, 
(v) furthermore I shall offer alms in honor of my departed relatives.
In five ways, young householder, the parents thus ministered to as the East by >their children, show their compassion:
(i) they restrain them from evil,
(ii) they encourage them to do good,
(iii) they train them for a profession, 
(iv) they arrange a suitable> marriage, 
(v) at the proper time they hand over their inheritance to them.
DN 31

This is no different to the instructions in any other major religion. 
Also, the suttas (Snp 1.6) literally condemn having sex with prostitutes. 

Unsatisfied with his own wife, with others’ wives he’s seen in tow,
  corrupted too with prostitutes— that’s the way to disaster’s woe.
Snp 1.6

The impression is contemporary Buddhism is so permissive because monks don't want to make any waves with Cultural Marxist Hollywood brainwashed laypeople, which monks view as "metta". 

user254: The third of the five precepts:


Kamesu micchacara veramani sikkhapadam samadiyami
  I undertake the precept to refrain from sexual misconduct.


The third of the eight precepts:


Abrahmacariya veramani sikkhapadam samadiyami
  I undertake the precept to refrain from sexual activity.


So the third precept is stricter in the "eight precept" version of the precepts, than in the "five precept" version.

These training rules [the eight precepts] are observed by laypeople during periods of intensive meditation practice and during uposatha (lunar observance) days. The Eight Precepts are based on the Five Precepts, with the third precept extended to prohibit all sexual activity and an additional three precepts that are especially supportive to meditation practice.

This answer quoted this introduction to the Five precepts, which says,

In many suttas regarding lay practice (Anguttara iii, 203), the
  Buddha explicitly warned of the five vices, which are dangers and
  enemies, and lead to hell. What are the five?
i) Killing living beings
  ii) Taking what is not given
  iii) Sexual misconduct
  iv) Telling lies
  v) Partaking of intoxicants

One who has these five vices lives the home-life without selfconfidence.
One who has these five vices breeds hatred in this life or breeds
  hatred in the life hereafter, feels in his mind pain and grief.
One who has these five vices is termed 'vicious' and arises in
  hell.

In the same suttas, the Buddha spoke of the advantages of
  cultivation of the five virtues, which are the Five Precepts, namely:
i) Abstention from killing living beings
  ii) Abstention from taking what is not given
  iii) Abstention from sexual misconduct
  iv) Abstention from telling lies
  v) Abstention from partaking of intoxicants

One who has these five virtues lives the home-life with
  complete self-confidence.
One who has these five virtues breeds no hatred in this life, or
  in the life hereafter, nor does he feel pain and grief.
One who has these five virtues is called virtuous and arises in
  the happy plane of existence.


I don't read that as being permissive. I read that as "this is the minimum standard of good behaviour needed to avoid being offensive towards other people -- to avoid harming other people."

The Five Precepts form the actual practice of morality for the
  layman. They are the minimum ethical code, which are mandatory
  for all lay disciples. They are undertaken immediately after the
  taking of the Three Refuges at every Buddhist service or ceremony
  and are administered by a monk if one is present; otherwise the lay
  disciples can do it by themselves. It is usual for devout lay disciples
  to undertake the Five Precepts as part of their daily recitation.

There's a definition of "misconduct":

This precept enjoins abstinence from improper or illicit sexual
  relations. The Atthasalini defines sexual misconduct as the volition
  arising in the body-door, through the unlawful intention of
  trespassing upon a person to whom one has no right of going.
  There are four conditions for wrong conduct in sexual pleasures.
i) There must be a man or woman with whom it is improper to
  have sexual intercourse.
  ii) There must be intention to have sexual intercourse with such a
  person.
  iii) Action must be taken to have such an intercourse.
  iv) There must be enjoyment from contact of the sexual organs.
With reference to the first condition, there are twenty kinds of
  women with whom men should have no sexual relations. They can
  be divided into three groups, namely: women under the
  guardianship of parents, family members, relatives and authorities
  charged with their care; married or betrothed women; bhikkhunis
  and religious women observing the Holy Life. For all women, a
  man forbidden by tradition or under religious rules is prohibited
  as a partner. For any unwilling partner who is drugged or forced to
  have sexual intercourse under threat of violence or coercion,
  conditions (ii) & (iv) exclude them from violation of the precept.

And it's not "to attain stream entry".
And I don't read it as permissive (e.g. "prostitution is encouraged"), instead I read it as protective, i.e., "don't do things which could break up families -- e.g. sexual activity with people who are married, and/or with the children who are under their protection -- nor which could interfere with someone who is leading the holy life."
It seems to me that according to one interpretation of the "3rd precept" of the 5 precepts one could even engage in various sexual acts with a vast number of prostitutes nonstop and that still wouldn't be considered as breaking the "3rd precept". (I am doubtful of it being possible to attain stream-entry with that indulgent behavior therefore I believe the Buddha did not teach that as being a way to attain stream-entry.)
So ... "sex with prostitutes is a way to attain stream entry" -- that doesn't sound like doctrine from the suttas, does it -- is someone saying that?
I think that the canon says that some lay people entered the stream. And I think that many lay people can and do keep the 3rd precept -- by being married or unmarried -- keeping the 3rd precept isn't bad -- and the precept doesn't require anyone to "engage in etc. with a etc.".
I don't much like to criticise other people's sex lives -- "You're too permissive! You naughty people! You shouldn't have any sexual activity, with your boyfriend/girlfriend -- even if you are both adults!" Instead I'm like, if a couple is happily married and of good behaviour then mudita and good luck to them -- but criticising people isn't something ... is that a good way to spend time?
Incidentally I'm not sure that prostitution is right livelihood. Doesn't the canon define 5 types of wrong livelihood for lay people -- i.e. trade in weapons, in poisons, in meat, in alcohol ... and, in human beings?
Also would you describe the first precept as "too permissive" -- would you ask, "Why is the first precept interpreted as 'no killing'? I don't believe the Buddha taught that torturing people without killing them is a way to stream entry'."
I don't think the precepts are "too permissive" -- I think they're as a good start. They're also kind of practical -- and common-sense, which everyone (even lay societies to which Buddhism is a new doctrine) might agree with.

14288: <p>It seems to me that according to one interpretation of the "3rd precept" of the 5 precepts one could even engage in various sexual acts with a vast number of prostitutes nonstop and that still wouldn't be considered as breaking the "3rd precept". (I am doubtful of it being possible to attain stream-entry with that indulgent behavior therefore I believe the Buddha did not teach that as being a way to attain stream-entry.) </p>

<p>Why has the "3rd precept" of the 5 precepts been interpreted as being so permissive?</p>

<p>I find it concerning how the "3rd precept" of the 5 precepts has been interpreted as being so permissive. </p>
 295: <p>Engaging in sex with someone who is not under another's protection or care does not break the precept. There can be prostitutes who may not fall into this category who are under their family's care but doing this on the sly. In this case, the 3rd precept may be broken. Also, there may be non-prostitutes who are not under protection. E.g. in western culture when one becomes independent and moves on to one shelter perhaps it can be thought of as been not under another's protection and care if they are totally not under the care or concern their parents and relatives. Therefore, sex in this context does not break the precepts.</p>

<p>To have sex one must develop sensory desire (kāmacchanda) which is one of the <a href="https://en.wikipedia.org/wiki/Five_hindrances" rel="nofollow noreferrer">5 hindrances</a>. This effective barrier to stream-entry. Though you are not breaking the precept, one is creating a barrier for its realisation.</p>
 8157: <p>I have explained the original Buddhist teachings about sexual conduct &amp; misconduct, before. </p>

<p>The 3rd precept in the Pali suttas (e.g. <a href="https://www.accesstoinsight.org/tipitaka/an/an10/an10.176.than.html" rel="nofollow noreferrer">AN 10.176</a>) says a daughter is to be "protected" by her family. </p>

<blockquote>
  <p>Abandoning sensual misconduct, he abstains from sensual misconduct. He
  does not get sexually involved with those who are protected by their
  mothers, their fathers, their brothers, their sisters, their
  relatives, or their Dhamma; those with husbands, those who entail
  punishments, or even those crowned with flowers by another man.</p>
  
  <p>AN 10.176</p>
</blockquote>

<p>Per the later <a href="https://buddhism.stackexchange.com/questions/1367/how-is-sexual-misconduct-explained-in-regards-to-the-five-precepts/1371#1371">Commentary</a>, the word "protected" means, per the <a href="https://www.accesstoinsight.org/tipitaka/dn/dn.31.0.nara.html" rel="nofollow noreferrer">DN 31 sutta</a>, the daughter is "restrained from unskillful behaviour" until the "parents arrange a suitable marriage" for her into a good family. </p>

<blockquote>
  <p>In five ways, young householder, a child should minister to his
  parents as the East:</p>
  
  <p>(i) Having supported me I shall support them,</p>
  
  <p>(ii) I shall do their duties, </p>
  
  <p>(iii) I shall keep the family tradition, </p>
  
  <p>(iv) I shall make > myself worthy of my inheritance, </p>
  
  <p>(v) furthermore I shall offer alms in honor of my departed relatives.</p>
  
  <p>In five ways, young householder, the parents thus ministered to as the East by >their children, show their compassion:</p>
  
  <p>(i) they restrain them from evil,</p>
  
  <p>(ii) they encourage them to do good,</p>
  
  <p>(iii) they train them for a profession, </p>
  
  <p>(iv) they arrange a suitable> marriage, </p>
  
  <p>(v) at the proper time they hand over their inheritance to them.</p>
  
  <p>DN 31</p>
</blockquote>

<p>This is no different to the instructions in any other major religion. </p>

<p>Also, the suttas (<a href="https://suttacentral.net/snp1.6/en/mills" rel="nofollow noreferrer">Snp 1.6</a>) literally condemn having sex with prostitutes. </p>

<blockquote>
  <p>Unsatisfied with his own wife, with others’ wives he’s seen in tow,
  corrupted too with prostitutes— that’s the way to disaster’s woe.</p>
  
  <p>Snp 1.6</p>
</blockquote>

<p>The impression is contemporary Buddhism is so permissive because monks don't want to make any waves with Cultural Marxist Hollywood brainwashed laypeople, which monks view as "metta". </p>
 254: <p>The third of the <a href="https://www.accesstoinsight.org/ptf/dhamma/sila/pancasila.html" rel="nofollow noreferrer">five precepts</a>:</p>

<blockquote>
  <ol start="3">
  <li><em>Kamesu micchacara veramani sikkhapadam samadiyami</em><br>
  I undertake the precept to refrain from sexual misconduct.</li>
  </ol>
</blockquote>

<p>The third of the <a href="https://www.accesstoinsight.org/ptf/dhamma/sila/atthasila.html" rel="nofollow noreferrer">eight precepts</a>:</p>

<blockquote>
  <ol start="3">
  <li><em>Abrahmacariya veramani sikkhapadam samadiyami</em><br>
  I undertake the precept to refrain from sexual activity.</li>
  </ol>
</blockquote>

<p>So the third precept is stricter in the "eight precept" version of the precepts, than in the "five precept" version.</p>

<blockquote>
  <p>These training rules [the eight precepts] are observed by laypeople during periods of intensive meditation practice and during uposatha (lunar observance) days. The Eight Precepts are based on the Five Precepts, with the third precept extended to prohibit all sexual activity and an additional three precepts that are especially supportive to meditation practice.</p>
</blockquote>

<p><a href="https://buddhism.stackexchange.com/a/9311/254">This answer</a> quoted <a href="http://www.urbandharma.org/pdf/PDF_BuddhismCourse/11_%20Five%20Precepts.pdf" rel="nofollow noreferrer">this introduction to the Five precepts</a>, which says,</p>

<blockquote>
  <p>In many suttas regarding lay practice (Anguttara iii, 203), the
  Buddha explicitly warned of the five vices, which are dangers and
  enemies, and lead to hell. What are the five?</p>
  
  <p>i) Killing living beings<br>
  ii) Taking what is not given<br>
  iii) Sexual misconduct<br>
  iv) Telling lies<br>
  v) Partaking of intoxicants</p>
  
  <ul>
  <li>One who has these five vices lives the home-life without selfconfidence.</li>
  <li>One who has these five vices breeds hatred in this life or breeds
  hatred in the life hereafter, feels in his mind pain and grief.</li>
  <li>One who has these five vices is termed 'vicious' and arises in
  hell.</li>
  </ul>
  
  <p>In the same suttas, the Buddha spoke of the advantages of
  cultivation of the five virtues, which are the Five Precepts, namely:</p>
  
  <p>i) Abstention from killing living beings<br>
  ii) Abstention from taking what is not given<br>
  iii) Abstention from sexual misconduct<br>
  iv) Abstention from telling lies<br>
  v) Abstention from partaking of intoxicants</p>
  
  <ul>
  <li>One who has these five virtues lives the home-life with
  complete self-confidence.</li>
  <li>One who has these five virtues breeds no hatred in this life, or
  in the life hereafter, nor does he feel pain and grief.</li>
  <li>One who has these five virtues is called virtuous and arises in
  the happy plane of existence.</li>
  </ul>
</blockquote>

<p>I don't read that as being permissive. I read that as "this is the minimum standard of good behaviour needed to avoid being offensive towards other people -- to avoid harming other people."</p>

<blockquote>
  <p>The Five Precepts form the actual practice of morality for the
  layman. They are the <strong>minimum</strong> ethical code, which are <strong>mandatory</strong>
  for all lay disciples. They are undertaken immediately after the
  taking of the Three Refuges at every Buddhist service or ceremony
  and are administered by a monk if one is present; otherwise the lay
  disciples can do it by themselves. It is usual for devout lay disciples
  to undertake the Five Precepts as part of their daily recitation.</p>
</blockquote>

<p>There's a definition of "misconduct":</p>

<blockquote>
  <p>This precept enjoins abstinence from improper or illicit sexual
  relations. The Atthasalini defines sexual misconduct as the volition
  arising in the body-door, through the unlawful intention of
  trespassing upon a person to whom one has no right of going.
  There are four conditions for wrong conduct in sexual pleasures.</p>
  
  <p>i) There must be a man or woman with whom it is improper to
  have sexual intercourse.<br>
  ii) There must be intention to have sexual intercourse with such a
  person.<br>
  iii) Action must be taken to have such an intercourse.<br>
  iv) There must be enjoyment from contact of the sexual organs.</p>
  
  <p>With reference to the first condition, there are twenty kinds of
  women with whom men should have no sexual relations. They can
  be divided into three groups, namely: women under the
  guardianship of parents, family members, relatives and authorities
  charged with their care; married or betrothed women; bhikkhunis
  and religious women observing the Holy Life. For all women, a
  man forbidden by tradition or under religious rules is prohibited
  as a partner. For any unwilling partner who is drugged or forced to
  have sexual intercourse under threat of violence or coercion,
  conditions (ii) &amp; (iv) exclude them from violation of the precept.</p>
</blockquote>

<p>And it's not "to attain stream entry".</p>

<p>And I don't read it as <em>permissive</em> (e.g. "prostitution is encouraged"), instead I read it as <em>protective</em>, i.e., "don't do things which could break up families -- e.g. sexual activity with people who are married, and/or with the children who are under their protection -- nor which could interfere with someone who is leading the holy life."</p>

<p><strong>It seems to me that according to one interpretation of the "3rd precept" of the 5 precepts one could even engage in various sexual acts with a vast number of prostitutes nonstop and that still wouldn't be considered as breaking the "3rd precept". (I am doubtful of it being possible to attain stream-entry with that indulgent behavior therefore I believe the Buddha did not teach that as being a way to attain stream-entry.)</strong></p>

<p>So ... "sex with prostitutes is a way to attain stream entry" -- that doesn't sound like doctrine from the suttas, does it -- is someone saying that?</p>

<p>I think that the canon says that some lay people entered the stream. And I think that many lay people can and do keep the 3rd precept -- by being married or unmarried -- keeping the 3rd precept isn't bad -- and the precept doesn't require anyone to "engage in etc. with a etc.".</p>

<p>I don't much like to criticise other people's sex lives -- "You're too permissive! You naughty people! You shouldn't have any sexual activity, with your boyfriend/girlfriend -- even if you are both adults!" Instead I'm like, if a couple is happily married and of good behaviour then <em>mudita</em> and good luck to them -- but criticising people isn't something ... is that a good way to spend time?</p>

<p>Incidentally I'm not sure that prostitution is right livelihood. Doesn't the canon define 5 types of wrong livelihood for lay people -- i.e. trade in weapons, in poisons, in meat, in alcohol ... and, in human beings?</p>

<p>Also would you describe the first precept as "too permissive" -- would you ask, "Why is the first precept interpreted as 'no killing'? I don't believe the Buddha taught that <em>torturing people without killing them</em> is a way to stream entry'."</p>

<p>I don't think the precepts are "too permissive" -- I think they're as a good start. They're also kind of practical -- and common-sense, which everyone (even lay societies to which Buddhism is a new doctrine) might agree with.</p>
