Using San Francisco as an example seems problematic to me.
The tech sector here is pushing everyone except other high-income types like bankers and lawyers out of the housing market, so cooks, servers, and bartenders can generally afford to live here only if they’ve been in a rent-controlled situation. If they lose that, they often move out of the area. A large percentage of the restaurant employees I talk with in LA moved there from here.
SF also has a local minimum wage (currently $13) which requires high-end restaurants to pay servers more even though with tips they’re already making two or three times what the rest of the staff do, plus a local health-care ordinance that applies to businesses with too few employees to trigger the Obamacare employer mandate.
On the other hand, people continue to open new restaurants in SF. Go figure.