Tanya,
Your facts are on the money, but it is hard to tell what you are getting at with your narrative, and it seems that you're inadvertently playing for the wrong side. I am not attacking you here, but you seem to speak as if qualified teachers would be treated differently. Well, believe it or not, qualified teachers have the same value to most schools as total imposters do. These businesses are not prepared to dish out better treatment or compensation, and they really do love their revolving door staffing strategy. It is a dealer's game and the school owners are the dealers.
No matter what the industry, dropping the wage (or letting it stagnate) hardly helps to attract higher caliber talent. Paying a living wage allows one to transparently discriminate against the unqualified, and rightfully so. The hardest hit here are the qualified teachers. That a terrible wage may or may not suit travelers just looking for beer money, is not exactly a matter of relevance to said teachers.
This is not a chicken and egg problem. Nor are the schools the victims. (Some of these schools charge students 500/hour for 1 to 1 classes).
The schools are not crappy due to being ground down by unqualified FTs. As you mentioned, they only want a white face and a pulse.
Good jobs attract talent. That talent is not in Kunming, but in Korea, Taiwan, UAE, Spain, Japan, and to a lesser extent in Beijing, Guangzhou, and Shanghai, because that is where the jobs are.
That talent would come here if serious positions were offered. Only the universities come anywhere close to offering anything, and when they do, the pay is quite low (though I still think it is a good gig.) The jobs aren't here and it is not the the fault of the teachers, the schools and other factors (local/provincial economy) are the generative side of this dialectic.
There is nothing wrong with teachers having higher standards.
ps. 150 is low now