There are many parts of the country where lavish acreages are built in communities far from town (save money on the land, put it into the house), banking on the automobile to commute thirty miles each way.

SF isn't even an anomaly here- look to the coastal mountains above Palo Alto. Lavish houses on large plots of land. Yeah, they are expensive, but you ain't getting no mansion and ten acres in the heart of SF for a paltry $50M.