It's not northern California where you have a vertically tiered forest with brush at the base and large pines. The palisades area is largely brush and small trees. Fires, even controlled fires, would remove just about all vegetation making the area even more susceptible to mud slides in the rainy season. Not to mention that controlled burns would be very difficult to control in the steep canyon settings where thousands of homes are present. But I do not think that is the issue here - it's more of homeowners desiring that setting and taking the risk knowing the fire (and mud slide) threat is ever present.
And there are prescribed burns in California - they are all in the north part of the state. Turn on the features on the map and you can see that.
https://ww2.arb.ca.gov/our-work/programs/prescribed-burningEdited by KC rules at 12:05:17 on 01/08/25