A couple random thoughts after reading...
Those on the Exeter buses are obviously not choosing the right routes. When DS was little (he's 7yo now), I had people offering to hold him all the time and people offering to help with the pushchair (although I had practiced at home, so could do it one-handed). A couple times, the elderly women that were holding DS told me "oh come sit by me, dear, so I can hold on to this little one just a bit longer."
Funny, some of them were.
I've seen a London bus driver turn off the bus and refuse to move until the pushchair person complied. Peer pressure is amazing - people were telling her just fold it or get off. She finally gave in (not happily, but too bad). And that was quite awhile ago.
As a parent of a child that uses a wheelchair, there is nothing more frustrating than having to explain to your 7yo (who also has comprehension problems and ASD) that "yes, the bus is here, but no we can't get on because there is a pushchair in the way. We'll have to wait for the next bus." And then having to explain it again when it happens again, while he is sobbing that he just wants to go home. While other people (not in a wheelchair) get on - so he sees that it's just us that can't get on. Cue complete meltdown.
Some days I think they ought to just limit radar keys properly and then put some type of barricade in front of the wheelchair spot on the bus that requires radar key.
But then that's just me.