San Francisco is the doyen of tech savvy urban economies, with the city and region hosting the who’s who of tech businesses impacting the world economy.

Google, Apple, Twitter, AirBNB, EBay, Yahoo, YouTube – you name it, they’re in the city or bay area. San Francisco is now rated an Alpha World city, top 10 in global financial city rankings. But there’s a worrying feature of their economy that could serve as a warning for Australian…