Hoisted from Comments: Noah writes:
No, This Is Not Surprising...: I wish they would adjust these things for cost of living (or at least housing prices). A family with two $75k earners is middle-class in the Bay Area, but is living high on the hog in Austin, Texas.
But (unless you really like JEN-U-INE Mex-Tex food, and love to go to the Salt Lick and sit outside on those July evenings when the temperature is still 110F at 9 PM) more people would rather live in San Francisco than in Austin: that is why living in San Francisco is so expensive.
Living in a nice place that is expensive because it is nice is one way to spend the money you have when you are relatively rich--it does not keep you from being relatively rich.