Professors tend to act more as managers/grant proposal writers/reviewers. The vast majority of individual contributor work is performed by grad students and pos

Professors tend to act more as managers/grant proposal writers/reviewers. The vast majority of individual contributor work is performed by grad students and post docs. This work is often intellectually challenging (well, in as much as moving science forward is), so there is a strong benefit for selecting the best prepared candidates. Chinese students that come to do their PhDs in the US tend to be very well prepared/selected (especially once you look at non-ivy league research universities, it is easier to get a super qualified chinese student vs a US native student). Now, there might be a price point at which you could attract more locals to go pursue a PhD, but right now it is just not a very financially attractive proposition. PhD students typically get a stipend in the 30-40k range, but perform the kind of work that on the outside would pay 100-200k (let's say for people after masters). Similarly post docs make 40-70k range, but if they went into industry they would make 100-300k (depending on field).