It is possible, but hard, to calculate human performance, it was done very scientific in aviation since ~ 1950. It is easier to do it if you consider 1% worst

It is possible, but hard, to calculate human performance, it was done very scientific in aviation since ~ 1950. It is easier to do it if you consider 1% worst drivers, either older people with long reaction times, distracted drivers, drunk drivers etc. If you have a car that is obeying all traffic rules, it never goes above the speed limit and it has sensors that makes it brake before rear-ending other cars you are already better than the 1% limit. It is a simplistic approach, just giving an example of how 99% is not that hard to reach.