Strange. That was the case for my first couple years, in classes with hundreds of students, where the university hadn't yet shed its "look to your left, look to your right" mentality. Later classes had fewer students and engaging professors, since they'd weeded out many of the worse students.
Its more a side effect. Everyone knows everyone cheats on the TOEFL yet it would be incredibly awkward in academia to discuss that issue, so its kinda glossed over to avoid massive interpersonal drama. But, yeah, any prof or TA you have who doesn't know English is a known cheater, violation of honor code, etc. It does make you wonder if their CV or transcript or reference letters or published papers are as fabricated as their obviously fake TOEFL scores.
Toefl is a surprisingly easy test to pass even with a strong non-native accent. I know people with mediocre to bad command on English who achieved scores of over 100 on the online test. There is no reason to cheat the system.
That may be, but several of my classmates in grad school told me that they regularly wrote their papers in Chinese and sent them to a translating service for English. These were students who were conversational in English. It makes you wonder how much the translator changed the content.
I am not acquainted with the Chinese system, but here in India, you have to personally go to the designated test centers and take the test. At the center there is some Airport level frisking before you get to see your computer and you need to have your passport with you to prove your identity (if I remember correctly). You are also not allowed to wear jackets/overcoats/caps while taking the test. Really very little chance for gaming this system.
It may have disappeared from the internet, but there was a great satirical newspaper at Georgia Tech back in 2001 or 2002 called "Shaft News". They ran an article about a calculus professor complaining, "How can I be expected to teach when the students don't even know basic Chinese?!"
