How do you come to the conclusion that autopilot is safer?

The Tesla press releases? It's the kind of uncritical analysis that you would expect from a company trying to market something.

Food for thought: By considering only automated and mnual driving you exclude basically all possibilities. Hybrid systems that are designed around the limitations of humans and machines seem to be a much more promising but less flashy solution if safety is the goal. This approach has a long history if you consider things like ABS and the traffic fatality statistics suggest it actually works. (Crash mitigation technologies surely muddy the waters.)