They have to work harder at school because they're competing with a higher density of kids. Students in Asia are under intense pressure to perform at school because lack of success often means a life of misery.
By comparison other races / cultures don't really have the same pressure.
We actually have the same pressure, but we have built ourselves a world where dealing with it has become somewhat optional. Why bust your ass when you know that you will be given a second/third/fourth/tenth/etc. chance anyway?
No wonder so many things are starting to fall apart around here.
Yes, Western societies have created economic and cultural systems that absorb the consequences of failure so well that individual pressure to succeed are no longer matters of survival.