China also has no problem killing trouble-makers. These spoiled only children come from upper class families or educated middle classes - farmers get 2 kids and the desperate poor often have illegal children and pay the fines. Only those who have been in the cities for two generations or were functionaries have this 4-2-1 family model.
So the educated class raise a few dysfunctional neurotics, while the underclass out-breed them. What does that tell you about the stability of such a society (there or here)?