I speak a bit of Chinese and have Chinese friends who were studying in Germany and one time I got to sit in on their copying session. I was quite surprised when a lot of Chinese showed up whom I'd never seen before.
Turns out some of them were seniors who had brought their homework from previous years. It wasn't like everyone just copied the work either, there was plenty of discussion about the points they had trouble understanding. (But my Chinese wasn't quite good enough to pick up on most of it.)
So if I may generalize from my anecdote, I'd say that Chinese students colluding is special in that they form a tightly knit community abroad, helping each other out.
One of the major benefits of being in a fraternity in my university was that the fraternities and sororities all had every homework and test most of the teachers at the school had ever released. I tests on the hardest math teacher in the school going back 36 years. I got asked a question on his final that he asked on his first and didn't ask in-between.
If he had spent more time teaching instead of coming up with insanely hard test questions we wouldn't have had that huge of a back file on him.
Again, is that special to the Chinese? Isn't US history filled with examples of foreigners forming tight-knit communities based on nationality or ethnicity?
My only other experience with large groups of foreign students from the same country was when I stayed in China as an exchange student and met a lot of Pakistanis.
They definitely hung out with each other more often, but they didn't seem to actually study much together. I had a few email me with questions on the same exercise, so at least those three hadn't exchanged notes.
Of course there might have been some Pakistani-only homework sessions I was simply never invited to, but I don't think that was the case.
Turns out some of them were seniors who had brought their homework from previous years. It wasn't like everyone just copied the work either, there was plenty of discussion about the points they had trouble understanding. (But my Chinese wasn't quite good enough to pick up on most of it.)
So if I may generalize from my anecdote, I'd say that Chinese students colluding is special in that they form a tightly knit community abroad, helping each other out.