As well as he/she has a professional driver paying close attention to whatever he does. Overseeing something is a really mentally trying thing and “fsd” car drivers will not be able to do that for long times.

You have it backwards. With humans driving there is a constant and unending stream of student drivers, because every new human must learn from scratch. There is no silver lining.

With self driving it takes longer for the one individual to learn, but the difference is that there is only the one individual, and it need not ever die. The learning is transferable between cars, regressions between generations need not be accepted. The problem of bad driving can finally be solved.