I think the long term answer here is to either not rebuild or mandate that the houses be built to a wildfire proof standard. Stucco, tile, ember and flame proof soffits etc... and maybe fire shutters and doors.
Though i was wrong about the no vegetation zone; it's 200 feet, not 20
That means sufficient land area per house and more than annual maintenance of that land. Both of these are expensive so people will not do them in California.