A simple google search, (which YOU could have done yourself), shows it's abut 1 in 1.5 million miles driven per accident with FSD vs 1 in 700,000 miles driven for mechanical cars. I'm no Teslastan, (I think they are over priced and deliberately for rich people only), but that's an improvement, a noticeable improvement.
And as a an old retired medic who has done his share of car accidents over nearly 20 years-- Yes, yes humans swerve off of perfectly straight roads and hit trees and anything else in the way also. And do so at a higher rate.
So would I need up upgrade to First Class to get that kind of service?