Why foreigner students are doing better than Americans?

Most of the time, the foreign students are better the American ones. They have problems with the language, but then so do the native speakers on my bright ẽample I know when I write my essay for me. But more often than not, native speakers are given a pass for poor spelling and grammar these are just minor issues. The foreign student, on the other hand, is penalized heavily, in part because they're less likely to complain and in part because many instructors have an implicit bias because they assume the English will be poor.