One would be forgiven to think a company like Facebook, with a market cap of 224.82B, would pay a little more?
[1]: http://money.cnn.com/2015/02/19/news/companies/walmart-wages...
[1] http://sfbay.craigslist.org/search/apa?maxAsk=833&bedrooms=1
And there are plenty of working class people living here. Were you under the impression that the working class people you see every day are all living somewhere else?
Its not something you normally pay attention too. I have a 8 person office in SF that I get cleaned weekly. I have no idea what those individuals are getting paid of the amount I pay to the cleaning service.