I agree with the OP.
This really comes down to a cost/benefits analysis. There is certain cost associated with staying in. While I agree that in more conservative, less educated, and poorer areas, "true" believers are more common, most in more liberal areas "believe" as long as the cost is not too great. That was me for several of the last years I was in, and probably true of many of us here.
The cost generally becomes too great when a personal situation arises, (whatever it may be), that allows one to realize that staying in is more expensive, (usually in terms of personal freedoms), than leaving.This is more common amongst the more liberal areas, since these generally have greater opportunities presented to JWs outside of the organization.
In most congregations I was associated with in the northeastern US, many JWs have college educations, careers, families with children, homes, etc. This is not the case everywhere. I also went to college in the Midwest, and saw a very different lifestyle amongst the JWs there, and that was 20+ years ago. The liberal folks, (and I was one of them), tend to remain JW, (in many ways a hedging of a bet), as long as it makes sense to. I think the GB know this, and hence, a big push against higher ed recently. People don't leave because they go to university, they tend to leave later in life as the opportunities presented allow a person to see they can have a good life post-JW. As soon as something happens, (a divorce, some injustice in the congregation, etc.), a person with such a life can easily come to the conclusion that putting more time and effort in the JW life is throwing good time and effort after bad. This is a much more difficult conclusion to come to when one's options are limited.
d4g