I never said anything about anyone being stupid. Uneducated =/= stupid. I'm merely saying that universal public education would be about the most immersion-breaking thing I'd ever seen in a game. Apprenticeships are very likely; schools are highly unlikely, being a very modern invention (really, 19th century in the way we would define schools).
How the heck would an education system be immersion breaking? I could easily imagine schoolhouses like the kind you see in Little House on the Prairie. They could even have a couple Deep Space 9-esque multicultural schools (which come to think of it is structured very much like the Little House on the Prairie school despite being on a sci-fi show).
To me, it would be immersion breaking (somewhat, I don't really concern myself with that concept much and just revel in the world presented to me) if this
thousands of years old society for no good reason never has any progression at all. You call school systems a modern invention but the world of Skyrim is many thousands of years longer running than our own civilizations. The reason for this some have given is that magical arts have stunted any need for more scientific study of the physical world. Instead magical studies provide equivalents to modern medicine, such as the ability to heal grave wounds or to purge disease (both of which are on a level far advanced in comparison to the real world in TES). All it takes is a skilled magician to heal someone to full health in TES... in some ways they are more advanced than we are due to their magic.