Well, I also think that there is a lot that we process 'in background' and learn on beforehand in order to learn how to drive and then drive. I think the most 'fair' would be to figure out absolute lowest age of kids that would allow them to perform well on streets behind steering wheel.

i am not making a point that it is, I am rather expanding on the possible perspective in which 16 years of training produce a human driver.

That being said, you don't really need training to understand a STOP sign by the time you are required to, its pretty damn clear, it being one of the simpler signs.

But you do get a lot of "cultural training" so to speak.