You've got to be kidding. Have you ever even gone hiking in those hills? Much of the terrain doesn't allow for heavy equipment use. The areas where the wildfires spread fastest are so rough and steep that even doing it by manual labor is extremely challenging. The state and local governments simply don't have that many workers (or goats), or the budget to pay for the work. The scale of the problem is immense.
Interestingly hills used to be considered a horrible place to build and poor shanty towns were constructed up the hill with the nicer parts of town in the valley. People didn't want to climb up the hill every day, you had problems with access to water and supplies. The ground was prone to shifting. You also had high winds and yeah, in fire prone areas, fire goes uphill.
What changed? Automobiles, reinforced concrete, retention walls, lift pumps, subsidized road construction.. People in LA with money now want their homes perched up a hill with inaccessible terrain covered in brush below it (that ensures nobody will build on their view!).
Same with oceanside land by the way. If you go to the shore of the bay of Biscay in France, for instance, the "seaside" villages are built not on the beach, but a few hundred yards inland. Building right on a sandy storm-swept shoreline would have seemed ludicrous when those towns were being constructed.
You're not making any sense. Even with roads, the terrain above and below the roads is largely inaccessible. If you haven't personally traveled through those areas then you might not be able to visualize the difficulty.
As for fences, what a stupid and pointless idea. The wildfires spread largely by embers blown up in the air, not by flaming debris being pushed across the ground. And what exactly are you going to build the fences out of?
In the vicinity of San Francisco, in the 80s, there was a big fire in a rural area, where every house but one burned to the ground. The one was untouched. One feature it had was a low masonry wall about 20 feet away from the house. The firemen quoted in the newspaper said that wall was instrumental in keeping rolling, burning debris away from the house.
Fires aren't always accompanied by high velocity winds. Lower velocity winds will pile up the embers behind various obstacles, like a low wall.
Masonry walls also are an obstacle for the wind, which will slow down near the ground, and behind the wall it will be still, which will result in debris falling to the ground.
The wall can also be made of chicken wire. It would be appropriate to experiment with various forms of inexpensive fencing like chicken wire.
As for hills, it isn't necessary to denude them completely of vegetation. Just the parts that are easily accessed, and alongside the roads.
I seriously doubt experienced wildfire firefighters would agree with your assessment that it's completely hopeless.
These aren't done more commonly in the LA area due to intense public opposition. It turns out people don't like inhaling smoke year round. Cities in general struggle to do things their citizens don't want them to do and it's not clear to me that this is a bad thing or something you can really blame the city for.
Sure, and here's what has changed between then and now:
1. A much longer and drier dry season
2. A much larger urban-wilderness interface
3. A much more organized public apparatus to combat environmental hazards (even in cases like this which require tradeoffs against more severe future risks)
The reason this is such a challenging problem today is not because everyone living in 2025 is a moron or morally corrupt and the people in the 70s were not.
