The other day a woman got on the bus with one of those double decker pushchairs. It was a busy bus, and people who got on later had to stand because she did not fold the pushchair down. She took her toddler out, and the toddler sat on a seat. She took her baby out ( and later put the baby on her knee when she sat down). She then picked her dog up, and put the dog in the bottom pushchair seat. So people were standing for the benefit of her dog!
Part of the problem is that some parents are selfish, and because they behave badly all parents could be penalised, as the government is looking at changing the rules on buses, in response to complaints from wheelchair users.
Because the wheelchair space is at the front of the bus where we live, mums tend to put the pushchair there and sit in the adjacent front seats to be near the baby. This means they are using up the seats that are meant to be for elderly and disabled people.
While we may think wheelchair users hardly ever get on buses, think of it the other way around. If you are in a wheelchair, almost every time you get on the bus, there will be a pushchair in the wheelchair space, and the parent may or may not be nice about moving it.
Buses that don't have steps in my area came in after I had my first child. If a woman had said then she couldn't get on the bus because she was incapable of folding a pushchair, it would have seemed ludicrous. People just did it. It was nice when the new buses made it easier, but people have abused the courtesy.