Since this is all based on a person's judgement, you're saying we should just basically ignore each other and never help someone as they should "have their stuff together" anyways?
What I'm proposing is that being in a wheelchair is not indication enough that a person is in need of one's assistance.
Just treat them the same as anyone else. This is important. It's not to coddle their self esteem. Here's why...
When a person moves from one point to another their brain processes what they see, computes the location, speed, and direction of any moving or static obstacles, and plots a course based on a prediction of where all of those objects will be at any given moment of the immediate future.
This whole process is largely autonomic. For mobility challenged, the portion of this where they control their travel is ~less~ automatic, which increases their reaction time to some degree, which makes the prediction portion of the process more important.
When people radically change their behavior without an actual cause, it can make the lives of people driving
ecv/wheelies more difficult.
* - I don't pretend to speak for mobility challenged people. I have a couple less abled friends, one of whom is dear to me and we talk on the subject a lot, but my commentary here is based on my development of an obstacle avoidance system for her power chair. The computer control must do with code what the human mind does subconsciously and all that is involved is pretty impressive. When I model the code behavior, I can set the unpredictability of moving obstacle (people) behavior and observe how much more computation is necessary vs. when moving obstacles are oblivious (ignoring). 10 years ago putting that sort of computer in a wheelchair wouldn't have been feasible. Now we put it in a quad-copter.