I can fold my McLaren with one hand, but I live on a steep windy road with bus drivers who don't help me on the bus, nor wait till I've sat down. So holding my toddler on one hip and folding with the other arm means no hands to steady myself, means we'll all fall over.
And I have it easy, really; one small cooperative toddler, an easy-fold pram (totally unsuitable for my roads, a complete pain to push to the bus stop, but my other pram, with bigger wheels and better suspension, isn't as good on the bus, so it's damned if you do, etc), all of us healthy and able-bodied. And it's still a huge pain, and I can only do it because I've never had a wheelchair board one of the buses around here and so I always stay unfolded.
(You wouldn't live around here if you were in a wheelchair, and had the choice, either. There's no pavement; you'd have to wheel yourself up a hill, on the road, in an area where people whip around blind corners. Terrifying)/
Of course wheelchair users take preference, that shouldn't even be a question. It wouldn't kill the bus drivers to be a bit more helpful around my way, though.