@ai6yr I’ve been pondering that for awhile. When I left San Diego, they were just starting to require better defensive measures for boundary communities – things like wide ice plant perimeters in addition to structural improvements – but that extra land is expensive.
I’m not sure low-density cities built around car travel can afford to defend sprawling fire perimeters, but anything more than modest density is expensive in earthquake country and a lot of people aren’t used to it and balk.