[Johnny555]

But many don't want to live in Mountain View, they want to live in SF (where the rents are close to what they'd pay in mountain view). With no traffic, that commute is around 45 minutes, during traffic it can easily be double or more.

[usaar333]

You are seeing different populations. I suspect people without kids on average prefer SF, while those with kids, on average, prefer the South Bay suburbs. (note: I am a recent transplant to Mt View from SF and have a toddler).

Consequently, SF companies have the same problems: the people without kids are nearby, but the ones with kids tend to be far away and are harder to hire.

There's no optimal location, unless you specifically are trying to select for junior vs. more senior talent.

> where the rents are close to what they'd pay in mountain view

Having just moved, I can assure you that Mt View rents are significantly lower than SF. For "nice area" (1990+ construction, convenient) 2-3 bedrooms, you are looking at something like $4+/sq foot/month in SoMa vs. ~$2.5/sq foot/month in Mt View (Palo Alto is considerably more expensive than Mt View and gets close to SF prices). That said, the reduced ability to live without a car cuts into the price savings significantly. (e.g. my family had to get a second car after moving)