This always grinds my gears (pun intended). Forcing everyone to live in a horribly dense, stifling, unhealthy situation isn't the issue. And the concept of saying LA isn't dense enough is beyond mind boggling, the number of people living there is beyond absurd. And yes, I know it's spread out, but the numbers don't lie, there's already more density than many places.
What this really is, is backdoor environmentalism. And I say that as someone that wants emissions down, reduced carbon, but a cat is a cat. And focusing on density to remove cars, because certain segments of the population rail against cars, isn't the problem people claim they are trying to solve.
For the roads? The easy way to pay for the roads, is to tax gas appropriately, and then ensure that tax only pays for roads. Nothing else, roads.
The second? Very clear end of year municipal budgets, showing how those funds were used.
Eventually, you'll reach a situation where the gas tax is the cost of road maintenance. And that's how it should be.
Back to the overall question? Well, I suppose you have quakes in LA, but outside of that concept, the US south is just about the easiest place to maintain roads.
In Canadaland, we have road damage due to freezing and thawing. Frost greaves for example, are where water gets under the pavement, freezes, and breaks it upward as the ice expands. No amount of drainage can fully protect from this, it just happens. And the cost for daily snow removal, ice mitigation(salt, etc), dirt being spread, the same for all the sidewalks isn't free.
LA has none of that. The US south doesn't, generally speaking.
LA doesn't have a road problem. It doesn't have a revenue problem. It has absurd infighting, like the entire rest of the US, with team politics and an inability to act as a result. It also has poor fiscal constraint.
Smaller LA side roads should last decades with proper maintenance.
But that's part of the problem too.
A tiny crack can be sealed, but leave it a year and it becomes a pothole.