Most of the time, the fare thru collect is nowhere near enough to pay for the service they offer. However, partially because is capitalism, they can’t give the service to for free because, well, reasons.

The fare is useful to track how many ride different lines at different times of day stuff like that. Plus, it gives a way to count how many people use the service for the purpose of getting grants and whatnot - which is what actually funds the bus service.

So, if the driver is in a hurry for any reason, he’ll often give you a free ride…cause actually paying the fare is, well, kinda for appearances, really…