Because doing infrastructure well - as opposed to holding it together with bubblegum and bailing wire - means spending money. And every dime spent is one dime less for shareholders.
As the saying goes: this suboptimal outcome is a feature, not a bug.
Building infrastructure well means telling people no. We have a problem with that in the US.
No. You cannot build in the floodplain.
No. You cannot build in the wildland urban interface.
No. You cannot build on a mudslide prone slope.
No. You cannot build in the surge zone.
We just don't do that. Instead we have a system where elect people to give us what we want without paying for the long term consequences. Simply put, we can't fix California, we don't have the money to. People in at risk areas need to be charged for the expense they add to the system, no new customers need added to the system.
If you wonder why the US doesn't build densely, it's because we don't pay for the true cost of our sprawl.
No that’s not how utilities work. Utilities are compensated for the approved capital they invest in infrastructure in the form of higher customer rates.
The upshot of this is that every utility in the country would love nothing more than to underground every overhead line in their service area. The reason this doesn’t happen is because public service commissions, who approve capital plans, aren’t willing to saddle customers with the astronomical costs of undergrounding lines (which runs $2-$3M per mile on distribution, depending on rock content of soil).
Let's say you want to bury a line 30 miles long. The upper end of your estimate is $90M. If the line services 50k customers, that's an average cost of $1,800 per customer. Charge an extra $50 on people's monthly bills for a period of 36 months, and your underground line is paid for.
It makes sense at the current rates. Solar can replace the entire grid. And instead of using large HVAC transmission lines, small communities can form small grids to help share battery stored energy (while still metered so the power usage is fair) or a resident could opt out of the community grid and do fully off grid solar as long as the had the ability to handle a few cloudy days.
PG&E has 81,000 miles of distribution lines. Even if they served all of California (they do not), that would be less than 15K customers for an average 30 mile segment.
As the saying goes: this suboptimal outcome is a feature, not a bug.