>Using a conservative cost-per-mile figure of $0.50 for the car and ignoring the bridge toll, the 37 road miles between those stations would cost over 5x more than the BART fare
Do note that the BART fare is heavily subsidized, actual costs[0] are closer to .40cents per passenger mile. So Bart is only slightly cheaper, by lets say 25cents per mile[1], than a car which is much faster, cleaner, serves a larger geographic area, and is far more convenient.
You must be taking different Bay Area transit than me (not that Bay area roads aren't hellish). Other than peak commute times cars are far faster to pretty everywhere BART serves outside of SF proper, and obviously much faster to anyplace BART doesn't.
The aforementioned Dublin > mission BART route is only about parity with driving for a 9:00am arrival in SF, and much slower after[0]. To say nothing of the obvious choke point that is the bay bridge, which would be well served by either an expansion or a hybrid approach. Robotaxi to west Oakland, hope on a bart, pick up a new robotaxi in SF to get to e.g. the sunset, or other not-bart served location.
Do note that the BART fare is heavily subsidized, actual costs[0] are closer to .40cents per passenger mile. So Bart is only slightly cheaper, by lets say 25cents per mile[1], than a car which is much faster, cleaner, serves a larger geographic area, and is far more convenient.
[0]https://www.bart.gov/kpi/stability .39$ in 2019, undoubtedly more now with inflation.
[1]2022 IRS deduction of 62.5cents