"Only" counts for something when you have to pay half of it to live in a reasonable location. That 90k in SF is around 50k in Hampton-Roads VA. That 90k in Oakland is around 60k.
Do people not commute from Oakland? Is the BART ride too long? Or are rents in Oakland just as high? I've only visited the Bay Area a few times, so please feel free to correct me on this one.
I managed to make do with 50K a year, but I lived in San Jose and didn't have the expenses of car ownership.
Living in SJ required a 20 minute walk to CalTrain and then a 45 minute ride to the city by CalTrain (if I caught the express) and then another 15 minute walk to work.
BART from Oakland only goes along Market, which is only walking distance from about half of SOMA (where most of the tech people work). That whole area can be pretty rough, especially after dark. Personally I'd rather walk to 4th & King and commute via Caltrain, but the peninsula is more expensive and Caltrain only has one stop in downtown SF vs 4 for BART (Embarcadero, Montgomery, Powell, Civic Center).
2. To some, yes, because BART is getting crowded so many end up standing in a wall to wall claustrophobic space.
3. They are climbing higher, especially since Uber is moving to there, and they're only the vanguard. It's also been discussed as a cheaper alternative to SF for at least two or three years now.
Are there no places available in the lower end range with 1 hour commutes? I know there is a shortage of low priced apartments, but they have to exist.