I'm not sure they always do. For one --- picture being a Chinese kid who needs a little extra help with math. They'd probably accuse you of being lazy or something. Plus since Asians tend (depending on the country they're from because not all Asian groups do equally well) to learn English and assimilate --- in a generation or two they're slipping down to everyone else's level.
I've met Koreans, Japanese,Chinese,etc. I've made very good friends with many Asian kids because our parents were exactly the same, constant drumbeat of education education education and if you failed a math test it was a major event. I remember an Asian friend remarking that black kids have it easy since no one expects them to do much (how sad). But yes I've also noticed with all ethnic groups these days kids slide right down going this way and that way but not in a good direction. I'm sounding old *LOL* but it's not all hopeless. For every kid that chucks the golden opportunities of America out the window someone is there to catch it.