You field logical fallacies of your own on a regular basis. Indeed, your gratuitous rudeness and sexism borders on ad hominem and is inappropriate here.
From this data, how do you conclude that American schools underperform?
If American schools with heterogenous student bodies* are preparing only one ethnic group to be competitive in international math comparisons, then they are certainly coming up short in other areas. The 'melting pot' is not a new concept in American education and while disparities in language ability, cultural mores, and economic condition present an additional challenge for American educators, addressing these disparities has long been a part of their mission and resources are allocated appropriate.
* It's reasonable to say that American schools serve a more ethnically and culturally diverse student body than the other examples cited here, notwithstanding the relative diversity of Singapore and Hong Kong by regional standards.