Actually, there is: non-compete clauses. They're unenforceable in California. Everywhere else, they are. That makes it an attractive place to be a tech worke

Actually, there is: non-compete clauses. They're unenforceable in California. Everywhere else, they are. That makes it an attractive place to be a tech worker, since tech workers tend to change jobs relatively quickly. In the Bay Area, you can easily switch jobs, even going to a competitor; this isn't the case in other states. And then you get the chicken-and-egg problem: with all those workers there, companies want to locate there to have access to that talent pool. And then the workers want to stay there so they have access to all those jobs that they can hop between.