FSD could be better than human drivers, or or could be worse. It doesn't matter, because in a situation like a tunnel where cars are traveling at high speed, in close quarters, with no place to escape, all that matters is that it is different. Highways and driving in general work because drivers have a reasonable expectation of how other drivers will react. When random drivers do something unexpected, what was a reasonable following distance is no longer enough. Add to that the limited amount of training data that Teslas have in extreme situations like developing accidents, and you have a near guarantee that something like this accident will happen now and then.
To be generous, Tesla FSD is a novice driver with some savant-level skills. Sometimes the savant talents save lives, but sometimes the novice reveals itself and bad things happen. In a reasonable world, this is what beta testing is about, and everyone involved in the beta test knows the risks. Tesla has decided to break the rules of beta by forcing these risks onto other people - drivers, cyclists and pedestrians - who have not signed up and are unaware they are part of the experiment. Effectively all of us on the road are Elon Musk's lab rats, like it or not. Or maybe we're his pylons.
In any case, Tesla's experiments in self driving in live traffic are so far over the ethical line that they should have been shut down on day one. The driver who turned on FSD in the Bay Bridge tunnel is an idiot who shouldn't be trusted again with any vehicle more dangerous than a bicycle. And we should all be glad there were no fuel trucks or hazardous cargoes in range of his stupid actions.