Can someone really be assigned to review in the APS’s editorial system for over a month without reacting at all and if yes, why? From observations as an author and reviewer that I made myself and that have been reported to by others, it seems that the editorial system of the American Physical Society (which in particular publishes the Physical Review journals) works as follows:


  
  The editor selects a reviewer.
  The reviewer receives an invitation to review, which he can accept, decline or ignore.
  If the reviewer declines, inform the editor to select a new reviewer (i.e., go back to step 1).
  Otherwise, wait approximately one month for a review.
  If nothing has happened, inform the editor to select a new reviewer.
  


This means in particular that if the reviewer does not react at all (for an extreme example, because he died years ago), it takes one month until another reviewer is selected. In contrast, with all other publishers, step 3 seems to be instead:


  3. If the reviewer declines or does not accept the invitation within a few days, inform the editor to select a new reviewer.


which seems much more reasonable to me, as a reviewer who does not accept to review (which usually is little work) for whatever reason is very unlikely to review a paper.

My questions regarding this are:


Does it really work like this?
If yes, why is the system not switched to one, which requires the reviewers to give some positive response within a few days?




Note: Just in case, somebody mistakes this for some disgruntled bashing: Apart from the above, my experience of publishing with APS journals has been rather positive. I am just puzzled by this seemingly nonsensical mode of operation.
Yes it really works like this, except that:
(a) the editor selects 1-2 reviewers, not a single reviewer (see http://journals.aps.org/authors/web-submission-guidelines-physical-review). In my experience / field, it's usually two.
(b) I'm not sure which APS journal you are submitting to, but for Physical Review B, the median time with referees is be about 30 days (Rapid Communications) or 40-50 days (regular) in 2013--see https://journals.aps.org/prb/rapids. This is roughly consistent with my experience.
Some journals are much faster.  In my experience in refereeing manuscripts, I'm usually given only 1-2 weeks to respond with "Yes I will review" / "No I will not review".  However, I'm usually allowed to request for an extension of the deadline (and there's usually a box where I'll need to give a justification for the extension).


A 1+ month wait may be a little bit longer than normal--you may wish to consider writing directly to the editor (and if the editor feels there is a need to do so, the editor may choose send an reminder email to the referee). Note that the referee could already be receiving reminder emails (auto-generated by the system)--I have received such emails as the deadline for review approaches.