Basically if you don't like a the laws/codes of a place, move.
I believe that's what these folks thought they were doing.
It also sounds like many of them have been there for decades, and the County is only now putting them in the crosshairs. Makes you wonder how many of the regulations they are being clobbered with are
ex post facto, enacted after the construction was done and therefore not applicable.
My house was built by my parents in 1950. There are a LOT of things that don't meet the current code for private homes, but were legal in this state in 1950. I am not required to change anything. The only legal requirement is that any new work has to meet current code.
The ADA does not apply in private, single-family residences. California, of course, probably has its own accessibility regs, but it's still pretty surprising to hear that they are being applied inside a private dwelling.