^ You need to have reasonable options for passengers when you don't give change, though. And that simply hasn't existed until recently.
Sorry, but I don't always have £1.85 to hand in exact coinage. The only places most people get coins is in change, very few normal people get them from the bank (although I have done so in the past - whether or not I'm normal is a matter for debate!). Any times I've traveled by bus, I've had to go out my way to manipulate the change in my pocket to ensure I have what the bus driver wants. And that just puts me off using the bus. If I only have a fiver then I'm possibly going to be out of pocket through no fault of my own.
Having mobile phone apps, smart cards and contactless payments makes the whole thing much better. You can abolish change on buses, whilst giving passengers plenty of opportunities to buy their ticket without cash.