I used to live in San Mateo. It’s a split-personality town. On the “wrong” side of the tracks are lower-income areas (by Bay Area standards), and the uphill side of town is where the multi-million dollar custom homes are located, just next to Hillsborough. San Mateo was once on a “top-ten most expensive cities in the U.S.” list.
That is pretty much true for most towns in the bay area.
Grew up in the East Bay Ghetto ran like hell two weeks before I turned 18 and never looked back.