Personally, I've got around a dozen transit cards spanning at least six countries...
[1] https://tfl.gov.uk/fares-and-payments/ways-to-pay/whats-the-...
Also a bit of avoiding fraud from driver's side - if the driver is allowed to take money out, it's impossible to control whether all the payments actually got to the end point.
That said, I've seen systems where the drivers give change - e.g. in Israel - and that's wasn't a big deal. So I guess it also depends on the locality.
Driver presses the button for a special ticket, customer inserts coins or bills, the machine automatically gives exact change. Alternatively, pay with NFC, card, etc.
Honestly some of the things mentioned in here are mind bending. I have public transport experience from both London and a small country on the eastern side of Europe, and both were efficient, fast and safe. What the fuck is wrong with the US when people are scared to take public transport because they can get robbed?
But I do agree that small transactions like that should be easier. Especially when a ride is $1.25. It's plausible that I might have a dollar on hand, but who carries around quarters these days?
The system here checks directly.
But yeah I guess transaction fees, we typically don't see them but the merchants do. I know of only two places where it's visible: a mobile kebab store charges 10ct and a local ice cream parlor just doesn't have it because of costs. Other than that every place I know offers it without (mention of) fees.
On a couple of occasions, I haven't been able to board a bus due to not having exact change. Once, I was with kids & family visiting NYC. We were planning to take a public bus from a suburb to the city. The fare turned out to be $16 for all of us, but I had $11 and some $100 bills. Guess what, I couldn't board the bus as they can't return change. The bus driver cannot accept partial fare from me. I couldn't give up 80+ dollars as change. If I had $20, I wouldn't mind not getting back $4.
I wondered why they cannot start accepting credit cards, Apple Pay, Android Pay or any reasonable alternative. I then had to find a train station nearby which could accept credit card.