These are companies that PG&E subcontracts with. Yes, they come on my property with no notice. Then fell trees or chop other things up, and leave. They are required by PGE regulation to leave a tag with their company name and phone number, but often they do not. So you have no idea who to call. If you call PGE, that is a total bureaucratic run-around.
There are 33,000 miles of power transmission lines in CA, and PG&E owns most of them. If they are not properly maintained and cause a wildfire-- they are liable. So they must do maintenance.
On my property, I have the many inspectors and inspections, all of them separate from each other and they rarely communicate or coordinate. Annual inspectors, semi-annual inspectors (separate), "enhanced vegetation management" inspectors, pole inspectors, line and support arm inspectors, infrared camera inspector, and a helo sometimes flies overhead doing inspections as well.