Then what do you do at the other end? Say you work at Apple as an administrative person. You can’t afford to live in Cupertino. So you drive from Fremont. The new BART extension will go from Warm Springs to Sunnyvale. Let’s say you extend it a bit further to Cupertino. So you drive to Warm Springs. Then park. Then you get off in Cupertino. Then what? There is no place you can put a station in Cupertino that even puts you walking distance to both Apple campuses, much less the other job centers in the city.
This is the problem all across the country. Most of the jobs in our metro areas are in the suburbs. Which means you’re talking about commutes that start and end in a car dependent area. There might be a reasonable rail route for a large part of the way, but you’d need to drive at both ends.
In addition to transporting people within an urban core itself, transit systems historically supported a hub and spoke model where people living in the suburbs took a train into their downtown job at the bank, ad agency, etc.
With relatively few exceptions, transit doesn't work terribly well for either travel from a suburban home to a suburban office park or, for that matter, out to the office park from a city apartment.
Where there are real clusters of offices in suburban locations, you can set up shuttles from train stations. But it's generally hard to service jobs that aren't either in the city or right next to a rail station.
This is the problem all across the country. Most of the jobs in our metro areas are in the suburbs. Which means you’re talking about commutes that start and end in a car dependent area. There might be a reasonable rail route for a large part of the way, but you’d need to drive at both ends.