When an elevator or space is designated HP only, then I feel it is OK to be rude to those who are apparently AB's. It's a lot of fun to try to get into a tiny single purpose elevator with a bunch of people trying to make room for me in my chair. I can get rather clumsy with my controls (accidently/on purpose) in such a situation.
This happened to me in Savannah GA. a few years back there are steps going down to the Riverfront and elevators for HP folks. It was quite a struggle to get in the elevator, but I was fairly new using the chair back then. Those were not marked HP only that I can recall.
Waiting in a line of walkees for an elevator sounds odd. Why wouldn't you go to the head of the line? And folks with heart ailments, etc. who must take an elevator should be up to the front of the line with you. Come on, folks, this is about respect, IMHO!
A Buddhist monk walked up to the guy working behind a hot dog cart and said, "Make me one with everything."
"Even what those with the greatest reputation for knowing it all claim to understand and defend are but opinions..." -Heraclitus
Yes, common sense would have strollers, etc. in them too.
Yes, non-disabled have the right to be lazy and take an elevator. You don't know why they are in line? On the other hand, they know why you are in line.