In this case, it's partly because PG&E negligence resulted in a massive gas explosion a few years back in Redwood City, and now no one trusts them to perform long-term maintenance on their infrastructure — and evidence is mounting that their unmaintained infrastructure is responsible for both this year's fire in California _and_ last year's.

So, everyone ought to do the things you describe, yes — but I can't fault residents of California for having a vested interest in keeping PG&E from burning them down every year, either.

EDIT: It would have cost them ~4x the original build cost to bury all those power lines in the forest, but they chose not to spend on infrastructure and may be bankrupted by their poor choices.