I'm not convinced. I am pretty sure I got a better education in specifically how we "know" (historically, anyways, eratosthenes and all that) the Earth was rou

I'm not convinced. I am pretty sure I got a better education in specifically how we "know" (historically, anyways, eratosthenes and all that) the Earth was round, by 7th grade in the US (public school, albeit a very good one), and having done equivalent coursework in a school run by the Japanese Embassy, you don't get that knowledge in the same way. Japanese education is much, much more like rote knowledge-learning than conceptual frameworks of thinking. If you made the opposite argument -- that flat earthers exist because in the US we teach conceptual frameworks and not rote memorization, I would be more persuaded.