I actually had the idea several weeks ago that bus companies should start using bitcoin, too, because they notoriously hate high value cash. They even need you to pay them with the exact amount. And sometimes it can be troublesome. Years ago I tried to take a bus with only a 20 euros bill and it was hell (yeah I know it wasn't smart in the first place haha, but I can't be the only one here to ever have been stuck at the door because of a similar problem).
If they accepted bitcoin life would be so much easier. You just pay and get in the bus. No need to worry about change.
Problem is that, at least in my country, bus companies are state-owned, and before you see state-owned companies start using bitcoin... a lot of time will have passed.
That's what they invented public transportation cards for. You automatically load them if your credit runs low and you just swipe it past the check in pole.
Sure, butcoin could be used here as well, but it is not like that is the only alternative to cash in the bus.