I've argued in several of these threads on self-driving the following point: safety in terms of fatalities per billion vehicle miles travelled (VMT) is already

I've argued in several of these threads on self-driving the following point: safety in terms of fatalities per billion vehicle miles travelled (VMT) is already in the single-digit range in Europe, and likely far below 1 fatality per billion VMT when restricted to "highways AND modern cars AND good conditions". So you need ridiculously huge samples to get statistically significant data on the safety of a single manufacturer's system. As in the order of magnitude of a hundred thousand miles per car for every one of the ~ 900k Teslas sold so far. Thus you reach a paradox: with current trends in "normal" car safety improvement, you won't know for sure if a particular self-driving model is safer than non-self-driving models until they are close to end-of-life. And then it's a bit late to find out.