This is not actually true. Although the conditions for permanent residence are pretty lenient on paper, they are hardly ever given out. Less than 5000 were issued in the 10 years to 2014 (in total, ie less than 500 per year). In practice it's FAR harder to get a Chinese green card than an American one.

Also, many of those 5000 "foreigners" are actually the children of senior Chinese officials who have taken foreign citizenship then returned to China. The number of "real" foreigners with permanent residence is even lower.