Was the California grid always private or was it run by the state government at one point? To me it makes no sense to privatize services where no competition is possible. You just end up with perverse incentives to do stuff like the above.
Theoretically, the grid is supervised by the California Public Utilities Commission, which has wide latitude to set standards and regulations for PG&E and others. The Public Utility Code is the highest law in the state of California[2], so IMHO a large part of the blame for PG&E's failures fall on CPUC's failed oversight[3][4]
[1]: https://www.eia.gov/todayinenergy/detail.php?id=40913
[2]: https://en.wikipedia.org/wiki/California_Public_Utilities_Co...
[3]: http://www.sfgate.com/bayarea/article/CPUC-head-Michael-Peev...
[4]: https://www.nbcbayarea.com/investigations/pge-probation-lift...
Of course, in 1896 an Edison company merged with the derivative of the original San Francisco Gas, to become San Francisco Gas and Electric. By 1905, that merged with something else to become PG&E.
[1] https://en.wikipedia.org/wiki/Pacific_Gas_and_Electric_Compa...
The wider "grid" is managed by CAISO - the independent system operator.
LA's utility is municipally run, in contrast to the big 3 IOUs in the state - PGE, SDGE, SCE.
SDGE had a 50 year exclusive franchise agreement with the city of San Diego that recently renewed under slightly different terms. Notably, and I'm paraphrasing: the city has the option after 10 years to terminate under certain conditions. [1]
Enron lobbied for, contributed to, and profited off of utility deregulation over 20 years ago. [2]
[1] https://www.kpbs.org/news/midday-edition/2020/07/27/sdges-50...
[2] https://www.consumerwatchdog.org/newsrelease/lesson-enron-el...