Neither do monopolies, like PG&E. Their profits are guaranteed at 10%, they can raise utility rates as they see fit, to cover expenses (The state has some influence, but it does not exercise it), and the shareholders are not personally liable for any malfeasance by the firm.

It's essentially a license to print money, with no incentives to improve. If you don't like their service, there's no competing power provider you can switch to. If you don't like them starting wildfires, you can sue them, and end up paying for your own lawsuit out of your next power bill. If you don't like them deferring maintenance, while paying shareholders dividends, you can... Complain on the internet?

At least with a state-owned utility, if you don't like how it's ran, you can always exercise your democratic rights to vote someone in who can fix it. Surely, of the 39.5 million people in California, you may be able to find one politician who knows how to run a business? Or knows how to hire managers that know how to run a business?