Clearly they do a lot of things right from a people perspective. [I'm sure there are exceptions.] They also seem to have picked a set of constraints that work well for them and their customers in (relatively upscale?) urban locations.

Also a very deliberate rollout strategy. I remember when they were I think only in California. There was a time when I was going out to Orange County a lot and our engineering manager one day doing some vaguely crazy driving to get to a Trader Joe's before heading back east on a plane.