Good question; the correct answer probably involves a long walk through the history of race in America. The fact is, people in our society tend, on average, to judge Asians as especially academically capable absent any other evidence, and vice versa for blacks and Latinos.
If you don't believe me, consider an analogous case of two people, otherwise identical, one with a strong southern accent and one with a strong English accent. It shouldn't surprise you that most white-collar employers would be biased toward hiring the person with the English accent. Biases like this are unfortunately common in our society (and in all societies).