As the sibling commenter suggested, it's not as simple as renting a mailbox -- HR departments and tax collection agencies are not that dumb.

However, I suspect that one reason the housing market has gotten so crazy (California perspective here) is that many Silicon Valley tech folks bought houses in Sacramento/Tahoe/$CHEAP_PLACE while also keeping their houses in SV but renting them out. As long as the rent payment covers most of the mortgage, they build equity and eventually own the house, while also having a nice big house to work remote from. And perhaps they quietly keep using the SV house as their official residence for HR/tax purposes.