If they live in a place with walking access to a shuttle (and enough walking distance amenities that they don't need a car), they're paying a lot in rent.

I wager you're paying more for car insurance than you spend on gas - car insurance is more expensive in the Bay Area than the rest of the country.

The price of gas certainly affects the contingent workers (guards, cooks, cleaners) whose work schedules don't line up with the shuttles.