Very interesting thread!
I don't know enough about japan to add any input but it's good that a lot of the conventional wisdom about their education system is chalenged.
just to add to the comparison, though, I would say that looking at primary and secondary schools is not necessarily important. it is agreed that the education system sucks at this level but that doesn't mean americans are stupid. A lot of the elite researchers still come out of american universities, which are still top ranked in the world (although all this is more balanced now with Europe and the rest of the world having more and more world class universities and research centers). But these elites do come out of this same educatrion system which sucks so bad. I'm glad I got my education in France but now I understand better how American schools work, that is, on a more self motivated basis. In the US if you are motivated you can usually achieve a lot, there are fewer restrictions, on the other hand if you are lazy not much will try to motivate you. The French system (I try not to generalize too much) standardises a lot, not unlike Japan, by using centrally designed programs and exams. It also stigmatizes a lot by promoting only the general branch of education (which leads to upper education) and leaves very few options once you get stuck in a branch (I don't know how I managed but there are exceptions). Also a big problem, which is more global I believe, is that university education does not lead to a secured job anymore, undermining the university system and giving less incentives to study more. the other side of that is the fact that now people who go to universities are usually motivated and want to learn something specific (I'm tempted to say that it is still a minority though). One last thing I will say is that, I've been studying in one of top universities in Europe (Uppsala, Sweden) with an exchange program and I believe there is still a big difference in what universities offer depending on the country. Subjectively, I think the American system is still the best in the world at the university level.

PS: Sweden doesn't have any final exam at the end of high school, or any entrance exam to university, a system that exist in a few other European countries. Everything is based on your grades during high school emphasizing a more constant demand rather than a very focused one such as in France. (correct me if I'm wrong)