Chinese students cheat because cheating is part of Chinese culture. Go to China and you'll be shocked at how little people care about others in public, or society at large.
This is a place where bystanders will watch cars swerve wildly around an open manhole cover over and over, nearly getting in accidents, doing nothing to help. When the Westerner comes by and closes the manhole cover, the Chinese are surprised. They'd never consider doing anything like that, because - what's in it for them?
This is a country where people pay others to go to prison for them. If they clip a child with their car, they'll deliberately run over the child again and again to make sure he dies and doesn't create hospital bills.
I was never more staggered by rampant, blatant cheating, plagiarism or dishonesty than when I spent a semester studying in a university there. For someone raised in the West, Chinese callousness and dishonesty towards strangers is unbelievable until you experience it.