China is less homogenous than you might think, and Japan has groups that face discrimination too even if the divisions are less obvious to Western eyes. And people do criticize Japan's relatively xenophobic attitudes.
More to the point, even if you were correct about their racial homogeneity that would not be a model that the United States can or should seek to emulate.
More to the point, even if you were correct about their racial homogeneity that would not be a model that the United States can or should seek to emulate.