[winterbourne]

This was interesting; thank you. He admits that he can't really answer this question. His point about technology seeming obvious in retrospect is similar to the Egg of Columbus idiom: https://en.wikipedia.org/wiki/Egg_of_Columbus

The video hints at the notion that they may just have not figured it out. Certainly working iron and steel would have been extremely useful, but they never developed that ability either, even after thousands of years of civilization. The interplay of a wheel and an axle may not be as intuitive as it seems to us in modern times.

One of the more esoteric explanations that I have heard is that there was a religious taboo around easing manual labor. And that the wheeled (and axled) figurines that we have found were not children's toys, but religious objects.