My city bans bikes from buses because of the space they take up. Scooters and folding bikes are ok only if they're folded up small enough not to be obstructive.
The really shitty thing is that bikes are allowed on trains. But if the trains are unavailable and get replaced by a rail replacement bus...because it's a bus, you can't take your bike.
I've heard that they used to have those here. But that they took too long to put your bike onto, causing buses to fall behind schedule. So they got rid of them.
A few years ago the same thing happened to me. There was someone who wasn't doing to good, on top of the station building on the next stop along throwing tiles and other things off. The operator got some replacement busses, that I couldn't get as I had my bike. So I just sat there with someone else who could get on as they had their dog. For about 4-5 hours. Sucked allot as I was tired, the dog was cute though.