Actually, much of what burned wasn’t in “known wildfire risk areas.” They were in neighborhoods that have stood for 50-75 years.
Most neighborhoods aren’t filled with chapparal (wild shrubbery). They have lawns or, in some cases, gravel “lawn” areas. Very few people expected that sort of combination of low humidity and wind. I lived in SoCal,for about 50 years, and most of the topime, the Santa Ana winds were pretty benign to built-up areas, especially in flat areas.
Clearly, conditions have changed over time. The natural fire cycle has been destroyed by well-meaning mismanagement of the shrublands, and we know that the climate is changing as well. I suspect new construction will require a lot more attention to fire safety, particularly as we learn just jow bad things can get.