Even without buggy or child it's often hard to get politely past the block of passengers between the driver and the wheelchair / buggy area to the empty (empty!) seats at the back of the bus, so I can understand that a mother with children might not be able to deploy scrupulously fair and understanding reasoning with other passengers as she tries to get past.

It's really quite dangerous, putting a toddler somewhere you hope it will remain stable, while the bus takes off and you fold the buggy. So while they ought to fold them, I can't really criticise other parents for leaving them unfolded. Happily, I find it a challenge. It's the nearest I come to the developing world gap year experience, and it makes me proud of my little nippers as they hold on grimly to the greasy yellow pole.

Wheelchair users are probably a rare sight because getting on is such a discouraging problem. They do have priority. Again, if it ever happened to me I'd probably enjoy the challenge moving everyone else out of the way so we can get off, but it might become less fun in time, and it's hardly safe with toddlers.

To get back to the start of the thread. You hope drivers could exercise their judgement, but often they can't, or they have given up, or else they're told not to. What the buses need are conductors, or more passenger co-operation. A while ago I was on a bus (without my children) and the driver was refusing to allow another buggy on. There was plenty of space so I smiled at a few (people I took to be) parents and rearranged the buggies myself. The driver accepted my lying reassurance that all the buggies were folded (he couldn't really see anyway) and off we went.

Lastly, about paying for buggies and children. The buses are a public service, and service priorities are determined largely by politicians we, the public, elect. No mayoral or council candidate could stand on a 'make babies pay' policy now and get in. Having babies is still a common human concern and voting is one of the few things we parents still have the opportunity for on sunny May evenings.