"safer than a human driver for years" can be misleading, since the system is supervised - it assists the human driver. So what we're comparing is human+FSD vs avg car (with whatever driver assist it has).
The claim that FSD+human is safer than an average car is old and has since been debunked: if instead of comparing vs all cars (old and new, with and without driver assistance) you compare like for like: other cars of similar price also with cruise control and lanekeeping assistance, then the Tesla cars are as safe as the others.
And to be clear, none of those are autonomous. There is a certification process for autonomous cars, followed by Waymo Mercedes and others. Tesla has not even started this process.
