While these are all good points, wit hthe possible exception of the previous poster, one very important point has not been raised.

The majority of Chinese students, and their parents, do not want non-native speakers teacing their children.

Forget everything about who is more qualified. Even the best educational instititions are also businesses, and it is in everyone's interest to keep their students and customers happy.

I have seen voracious complaints received on unsuspecting management for offerring a Phillipino as a native speaker.

The fact is that it is common sense to please your customers and students. Teachers from the USA andthe UK do this far better that equally qualified people from other Asian or African countries.