This was illustrated in a chart[0] by someone on the Tesla subreddit just yesterday.
Using Autopilot is in general much safer even though it does from time to time make fatal mistakes that human would not do. (Like when it fails to recognise a truck and tries to drive through it[1].)
Of course AP is a very different thing to FSD, so this doesn't speak anything about current nor future FSD safety.
[0] Autopilot safety comparison https://www.reddit.com/r/teslamotors/comments/jim86m/i_graph...
[1] Accident https://electrek.co/2019/03/01/tesla-driver-crash-truck-trai...
The right metric is simply a much lower accident and fatality rates for self-driving cars.
This flexibility reduces the challenge for self-driving cars since they are far from understanding situations at the level people potentially can, but still results in a safety win.