If humans did the crazy stuff on the road at the same rate as we've seen from the few select hours of FSD driving uploaded by Tesla owners (who are fans and more likely trying to show it at it's best) this week, we'd all be dead.

Do people randomly brake at high speeds for no reason ? Tesla cars do:

https://m.youtube.com/watch?v=xj73Q3lWvFM

All the time. Witness the effects of cellphones/children/food/spilled food/makeup/jarring news/exciting music/significant others/attractive people/gawking at random bits of interest. Also, brake-checking just cause' and for insurance fraud.

If what you're proposing is that "success" in this experiment is that every Tesla now drives at least as well as the absolute worst-case human driver, then you've pretty much articulated why this experiment is so dangerous.

The thing is these are not the "absolute worst-case human driver", these are the absolute average human drivers.

People get easily distracted, get excited, get tired, all of which are propitious to bad decision-making.

Many human drivers are downright dangerous, but that's not a reason to add dangerous machine drivers on the road, either.

The adaptive cruise control in my Honda is also bad about braking without good cause. Of course, they don’t market it as “self-driving”.

Automatic emergency braking also has false positives.

Who is legally responsible for the car doing something crazy? Will engineers or executives go to jail?