Imagine some asshole puts an incendiary in an orphanage, and rigs it to go off when a nearby speed trap detects someone going more than 10mph over. Eventually, someone does, and the orphanage catches fire. Further, the group responsible for constructing and maintaining the orphanage hasn't looked at the place for 50 years, and so all the orphans are trapped inside and die.
Who's at fault? Obviously the the asshole, and almost certainly the maintainer. But the driver? They were the direct cause of everything, and had they not broken the law those orphans would still be alive! Right?
But most people will identify the driver as being at worst minimally at fault. They may have triggered things, and it may have even been predictable that speeding could kill someone, but someone was going to come along and trigger things eventually, or the speed trap would misfire, or lightning would strike the orphanage and cause a fire directly.
To me, PG&E is the driver here. Yes, they didn't do maintenance they should have. But as fires have demonstrated this year... fires are going to happen. Lightning, gender reveals, a broken muffler... Something will provide the spark. So instead we should blame the people who set up the situation such that a fire in the wrong place could kill dozens.
Which, IMO, is two things. One is the set of forestry management practices that lets brush build up to the point that crown fires are inevitable - which we do by putting out all fires as soon as possible - and the second is constructing houses to be vulnerable to forest fires. Forest fire proof construction is possible! It's just not quite so cheap, or might not allow a tree right up next to a house in the most aesthetically pleasing fashion.
But until we fix at least one of (and preferably both of) those things, fires like this will keep happening. No matter how much PG&E gets fined.