Even though Western values are quickly taking root here, (via the movies, music, etc.), there exists a tremendous amount of cultural pressure to "excel academically" (for some definition of this idea). I speak mainly for China because that is the education system I'm most familiar with, but I assume that we can find similar patterns in other Asian cultures: mom and dad work 5 am to 8 pm selling egg pancakes for 50 cents a pop on the side of the street while little Johnny (or Jenny) goes to school from 7 am to 4 pm with a two hour break between 12 pm and 2 pm. When they get home, they get to look forward to 6 hours of homework. No going to soccer, maybe some piano lessons if you're rich enough. Certainly no time for video games, making out with your girlfriend, creating a gang, doing drugs (although there are exceptions, I'm speaking in broad generalizations here…).
But there does not exist this idea that you can be who you want to be, that somehow you can have a good life by developing other talents. There's also not this idea that you have a choice. I've encountered college students that tell me that they /have to/ graduate. This means that if they don't pass their tests, they will find some other way to get their diploma.
Compare this to your typical attitudes towards education in America. I'm not saying that one is better than the other, I'm just saying that there is so much pressure engrained in certain cultures "to do well" (i.e. score high on a standardized test) that makes it hard for American culture to compete.
This explanation does not explain why European cultures fare much better. I'd love to hear what some of the cultural attitudes towards education are from there as well as the strength of family influence.