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.
I was until now unaware that there were places where (non-folded) bikes were allowed on buses. On trams and trains sure, but buses have such limited space that I can't imagine a bike being transported in them.
Not much more difficult to accommodate than wheelchairs or prams. Actually easier in many cases because the operator or probably more fit and the object more insensitive to placement.
The shape can be unwieldy because of the length, though.
Trains used to be the same here (with the exception that you could always take your bike on the train during peak hours in the non-peak direction, it was only peak direction that was banned), until they were trying to get people back on public transport after/late during the pandemic. Then they started allowing it even in peak hours, with some weird limitations like a maximum of 2 bikes per car, and only in the first or last car of the train.
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.