There are tons of banks, everywhere. Most are unmarked, and arent even 24/7's on the outside. But none in San Fierro. Except the one near Mt. Chiliad. Which is too far, since i think we can all agree that 90% of players are too lazy to drive there.
(Including myself)
But we cant just put a 24/7 in San Fierro, without a building to put it in. I've driven around the city, and there really arent any buildings that we could use.