As it turns out it doesn't actually cost that much on regular transit, there's an AIRPORT SURCHARGE because it's an "airport train".
No wonder Americans don't use public transit, even when the system exists it's ridiculously difficult and expensive to use.
for bart, it charges by the distance, for muni, they recently up thier fees for tickets, they are also have a budget mismangment issue which causes thier budget problems. they waste twice as much as they bring in through fare evasion fees, and transit fees, last i heard they are cutting some services in the summer. and there has some justification for fare evasion(just dont discuss this on reddit, because its mostly been infiltrated by do-gooders conservatives)
caltrain is a seperate agency than, bart, muni.
the mismangment parts: 1 of the problem is they spent twice as much as they are recouping in transit fees, lik 6+ million hiring inspectors over 2-3 million in fees. visit the reddit subs for more info.