There's a mechanism in place that you're probably not aware of, but which you should research well and think about. Any time that a closed question is edited, it is put into a review queue called Reopen Votes, for which the options are Leave Closed, Edit and Reopen, and Reopen. If a question gets three 'Leave closed' votes, then it gets taken out of the queue - which means that three independent people think that the edits are not enough to warrant reopening. It also means that they get to see and comment on the post, if there is evidence that the OP is on the track to clarify their ideas but still needs some help - and this does happen very often.
For more information, see this Mother Meta post:
Add a "Review posts with reopen votes" review task?
Your assertion that 'a closing vote can never be removed' is incorrect - it takes equal amounts of people to reopen as it does to close.
Now, I cannot account for the actions of other reviewers on that queue, but I can assure you that each question I see there receives a good look at both the changes and how they address the closure reason, as well as whether the new version by itself is a closable question or not. Unfortunately, I agree completely with Kyle in that the content of this queue is very often minor edits which do not address the closure reason at all.
To browse through the last few questions on the queue:
Against this background, a substantial edit which has clearer language or a longer posts immediately demands attention, and it is easy to detect when the OP has put in a good bit of work to clarify their post. If they have clarified it to the point that the core of the question is now clear, I will usually edit it into shape and vote to reopen.
However, this is very seldom the case. Most often, the lack of clarity in the language leads to ambiguities in what the question actually is (if not a complete puzzle as to what was going on inside the OP's head). In the (relatively frequent) cases where one can identify two or three candidate questions that the OP may be thinking of, it is still a disservice to the OP to directly edit that in, because we do not know what they wanted to ask.
Finally, beware of making generalizations based on your own personal experience of the site, as I can tell you - from experience - that it is very easy to not see stuff that does go on. Unless you have followed up on every post that was closed as unclear, and seen that all of them get worked on by their OPs and still get 'robo-voted' down, how can you be sure that you've not simply been seeing the closure part of the process, without being around for the reopening?