So yeah, I hope the airline gets screwed hard for this but I still can't picture this:
“It took us struggling, in front of a dozen people as some looked away and others looked on with shame, to get him off that plane..."
wtf didn't anyone offer some help? Two dudes under each arm? Something? Oh nah, let's let the guy drag his ass off the plane with his old lady holding his feet, OK.
Airlines won't let passengers use their own wheelchairs on the plane because the aisles are too narrow.
Normally the airline has transfer wheelchairs available at the gate that are designed to fit in the plane for the purpose of moving passengers on and off the plane.
Because it's the law and is their actual legal responsibility? Take it up with lawmakers if you think that's ridiculous, but generally most western societies have (rightly imho) decided that disabled people should have the ability to get around and that businesses need to accommodate that. Since the airlines won't let passengers take their own wheelchairs on board, then they need to assist those passengers in getting to their wheelchairs.
Honestly, the part I don't get about this story is that there are wheelchairs everywhere in airports. That's what seems ridiculous. Someone could have grabbed one even if the airline didn't have one on board.