I think that it would be a good idea to bury power lines but when it comes to spending money on infrastructure nobody wants to pay for it.
It is not only cost. Putting lines underground is not a panacea either. They cannot bury them too deeply, as ground movement (earthquakes, remember?) can also damage them. Even in the relatively few areas that are geologically stable - and on the entire West Coast those areas are VERY few - those areas are surrounded by, and part of, extreme terrain.
Much of what burns in NorCA is forest (the 2018 Mendocino fires started originally in a National parklands and spread south) or mountainous terrain. You cannot put lines underground easily. Even with today's heavy equipment it is hard/expensive and sometimes impossible merely to build a
road.
This is the reason why NorCA gets larger fires with fewer homes burned than SoCA fires - they have flatter terrain, and have built outwards continuously over decades.
It's why in the West Coast you can drive north/south easily and relatively quickly - but east/west is another matter altogether. The same distance in miles can take you twice as long to drive; the roads are narrow two-lane jobs that regularly wash out from erosion, built back when logging camps could still dynamite a road from Point A to Point B - and even they didn't find it possible to build in a straight line.
I no longer have much sympathy or patience with the folks in Paradise CA. A lot of statistics and stories came out afterwards, and it was shown that particular area is a
historical firetrap. It is geographically located where fires enhanced by high winds are especially prevalent. It has suffered severe wildfires
over 50 times since CA became a state in 1850.