How to ensure committee reads and comments on dissertation draft prior to final examination? The constructive question is, What practices/strategies could help ensure the committee reads the dissertation?

I am wondering if those who already hold a PhD, or advanced graduate students finishing their dissertations have experience where they suspected that their committee (besides their Chair) have not read their dissertation prior to the final defense examination. I would guess this issue is far from unique, as there is a variety of reasons for this. Here are some general reasons: 


Gap in Access: Committee members become separated from the department/institution, either completely or to some significant extent. Examples include retirements, where the individual might remain tangentially involved in a part time or 'emeritus' role; leaving for another job at a different institution, etc. (both are often associated with geographic relocation). 


This creates additional distance between the student and that individual, making an "office drop-in" unfeasible and communication more lopsided, as the individual may feel less press to respond to emails/calls. 

Note: difficulties with communication can be a standalone category, but I thought it was too broad as it applies across the board.


Gap in Motivation: This is essentially a gap between committee member's current priorities/interests and the thesis. Committee members, who have been added to the thesis committee because their area of expertise complements the knowledge capital on the committee, might feel disinterested from the particular dissertation topic selected by the student. Because the topic does not directly tie into their work, there is little incentive for them to spend time carefully reviewing the dissertation. 
Lack of time/low priority: Related to the previous reasons, although this  issue might surface even if the faculty member is reasonably accessible (on campus etc.) and reasonably interested in the thesis. Despite their 'well meaning' and 'best intentions', the thesis nevertheless keeps slipping to the bottom of their to-do's and they don't get around to reading/commenting for months. The pattern may recur despite regular polite reminders by email from the student and/or the committee chair.


Whatever the underlying reason (or their combinations), the result is the same: the thesis does not receive as thorough review as it technically should. The obvious negative consequences may be summarized as:


lower overall quality of the thesis (more eyes on the writing helps
spot all sorts of issues that may be visible only from the unique
vantage points of highly competent readers); 
lower quality of the student's learning experience (less feedback = less learning); 
longer time to complete thesis (since the student has to compensate for lack of feedback by trying to work out all the kinks on his/her own, plus the time it takes to simply wait for committee members to respond to requests for feedback).
difficulties during the final examination (thesis defense), since lack of committee's familiarity with the content of the thesis directly impacts their ability to be more "plugged in" to the examination presentation and 'grilling' of the candidate. As a result the candidate might have incorrect assumptions/expectations of the committee's knowledge of what he/she is talking about, and the resulting general confusion (can anyone relate to that one? ;)


What to do. How to reduce the chances of the 'neglected thesis syndrome'?
This is a real problem in practice. Basically everyone I know (and this, at times, includes me -- though I make it a point to set aside sufficient time to mark it up throughout and return the comments to the student) reads theses the day before the defense, with all of the consequences you mention. I have had more than one case where a student thought that receiving no comments meant that everyone was ok with the content of the thesis, just to find out that the defense did not go well and the committee wanted to have substantial additional work before they will approve the thesis. Not good.

I think the most common cause is that committee members simply don't have the time. To read and mark up a 150 page thesis thoroughly takes well over a day of full time work. To a committee member, this is unproductive work -- no publications will come of it, no grant funding, very little appreciation by the department. So it slips to the bottom of the todo list until it can't be pushed off any more (the day before the defense).

The second most important cause is that theses never get finished on time. I have received theses from candidates the day before the defense -- that's definitely not enough time and the candidates should have known better. I now ask that they at least send me the draft they have two weeks before the defense, but not always are they in a form that makes it worth reading through.

In the end, there is probably little you can do to affect the underlying problem, which is that committee members have little motivation to give a candidate good feedback. Your best bet is to keep them up to date with regard to what you do: make an appointment to go see them every 6 months and tell them what you have been doing; if you have drafts of individual chapters, send it to your committee members as soon as you have it; invite them to seminar talks you give; etc. Build a relationship. If a committee member is interested and feels engaged, you're more likely to get good feedback at a time when it's useful. 

On the other hand, if the only time when you see your committee members is (i) when you enlist them to your committee, (ii) for your proposal defense, (iii) for your final defense, and if you give them the draft of your thesis 3 days before the defense, then don't be surprised if you get negative comments during the defense or in reply to your thesis.