Those jobs are hard to do remotely because they involve providing services to other people who live in the area - in the case of San Francisco, that's mostly te

Those jobs are hard to do remotely because they involve providing services to other people who live in the area - in the case of San Francisco, that's mostly tech industry workers who could work remotely but don't for reasons of industry politics. The hairdressers and mechanics and waiters required to service them act as a multiplier on the resulting population growth, but the cause is all the jobs that could be done remotely but aren't. Every tech firm that insists on operating from SF leads to a penumbra of non-tech workers around it being stuck in SF in jobs that cannot be done remotely.