A lot of the fault surely lies with the bus companies, the bus drivers are not willing to wait while a mum folds the pushchair, they will just drive off before all the children are sat down and held securely and it's this that makes it a nightmare for mums.
It's pretty intimidating having a driver huff and puff at you and roll his eyes etc while you get more and more flustered trying to juggle shopping, several small children, change bag, drinks and the pram. I think most mums would fold if given the chance to, and helped to rather than being stared at by everyone on the bus.
There is also no way of refunding ticket money if you decide it's easier to just get off and wait for the next bus, some sort of stamp perhaps so ticket was valid on the next bus?
I have used the bus in the days before the pram could be pushed straight on with various nieces and nephews, back in those days as you knew pram needed to be folded you were waiting at the bus stop with pram folded ready, everything in one backpack/bag, children knew to get on quickly if capable and sit down and hold on, there was a rack at the front to stick the pram in - I notice my local buses don't have a rack now, and then I would always walk home as it just wasn't possible with a load of shopping as well as several children.
I thank goodness I am capable of walking most of the time, had to use the bus recently because of a broken toe but it must be awful to have no choice all the time - it wasn't a good experience.
Oh and my local buses have a sign up saying wheelchairs DO NOT have priority over pushchairs, was surprised at this.