You being a professor, I have a question for you.
I suspect it’s because foreign students have better math skills. To often I’ve seen students treat college as a vocational school. They think it’s better to have “hands on” work. That fine I think, if one is leaving soon. However without learning basic advanced mathematics, beyond the fourth semester of calculus, they are ill prepared for graduate school. What do you think of that idea?
No question that many foreign students have better math skills, but their communication skills in English are pathetic and their analytical skills are about even with domestics. In the biosciences, where advanced math is less important, the written/spoken language requires greater emphasis. It is an extra burden on advisors to have to rewrite anything put forward by most foreign grad students who can neither speak nor write effectively.