Salaries in the LA basin and San Diego have been in a ghetto since forever, it's really well known. The theory is that there's a lot of surfers that will take a big salary hit to live near the So.Cal. beaches, so it has a permanent depressing effect on salaries. Maybe that's the reason, maybe not, but the fact is that people in LA with skills can instantly double their salary by moving to the Bay.

Given the cost of living in the area, 70k for a senior developer is a nightmare for everyone, but the fact is there's no shortage of people willing to make the trade so it works for you guys and that is fine. There's a bit of a blowback though, because of the low salaries and beliefs they are normal, it's not the best place to start a company doing anything cutting edge that requires the top tier of talent, and that's why all the really cool stuff is still in the Bay and will probably always be there.