I do not regard Musk as an authority
More a lose canon who has done some good things but also made some big mistakes. A typical entrepreneur really taking big risks sometimes with other people's money.
Mr Musk is fallible as the rest of us really, just a lot braver. He did have a huge push to go for total automation on the initial Model 3 production line and had to back off which is when he made the comment about humans. Humans have admirable flexibility and can adapt to the unexpected better than any current automated driving system which is why there are no Class 5 systems out there yet.
Evolution has prepared humans fairly well for the task of driving. We all have ancestors who were successful hunter gatherers, they detected and reacted to threats like predators whilst being effective predators themselves. The unsuccessful ones did not have descendants. Driving is not all that dissimilar and nor is playing football. Those involved need to be aware of the world around them and react to often subtle signs which requires experience and reasoning to reduce false conclusions.
For Australians the difference between a tree stump and a kangaroo can be quite important and there is not time for a really good look. It is that sort of reasoning which for the moment at least has evaded most AI. They cannot yet draw conclusions and as one US expert (I am not) noted, it might be better to call the current state of the art Advanced Statistics.