I also think they know. My guess is it’s arson and economic terrorism. Just too many massive fires in high cost housing areas lately. But that’s just my opinion.
Fire investigators can easily pinpoint causes by going over the point of origin. Downed lines? Road flares? Signs of gasoline or other stuff on the dirt or in ashes? Easy. They know how these fires started. They just aren’t saying. Sure, Santa Ana winds, dry brush, etc but it takes something to start a fire besides weather and fuel. And lightning can be ruled out as there were no storms.