Have you ever seen how big the US is?!? Rail systems work in Europe because densities are extremely high.
The closest city to the Bay Area is Sacramento which is 90mi/150km - which is the maximum distance that a commuter rail system can work between two metropolitan areas while still being cheaper than flying.
San Francisco to Los Angeles is 620-700km - so from Cologne to Prague.
Unlike that route, you'd need to be building through multiple mountain ranges in California AND there are very few cities in between to justify ridership.
The closest city to the Bay Area is Sacramento which is 90mi/150km - which is the maximum distance that a commuter rail system can work between two metropolitan areas while still being cheaper than flying.
San Francisco to Los Angeles is 620-700km - so from Cologne to Prague.
Unlike that route, you'd need to be building through multiple mountain ranges in California AND there are very few cities in between to justify ridership.