The central point here (well, to me!) is that there are many questions that have accepted answers, yet ZERO up votes. That has nothing to do with "drive-by" users, or lack of community. It means that the person who asked the question DID stick around long enough to accept an answer. If the person did that, then WHY couldn't that person at least click ONE MORE TIME, so that the accepted answer had a single up vote of appreciation?
This irritates me to no end! Obviously... Actually, it is not unique to WebApps SE. You are quite friendly and courteous here. I have seen this sort of thing, namely, accepted answers with zero up votes, on many SE sites, quite often.
I DO agree with @ChrisF in that there isn't a lot the system can do to encourage people to vote.
Oddly enough, there are registered users (again, on other SE sites, not on WebApps necessarily, though I haven't looked), who regularly ask and answer questions, over a period of a year or more, but NEVER ONCE up voted any answer. I don't know what is going on with that! It is probably a vagary of the human psyche. I am at a loss to explain though. (I wish I could directly deliver a lecture on the virtues of compassion and respect for others to such individuals, but, well, that isn't possible.... ;o)