Yeah I don't about Vietnam but in China they cheerfully poop on supply and demand rules. The demand for Foreign Teachers probably outweigh the supply by 10 to 1 and yet they keep offering miserable salaries, treat their teachers like unwanted commodities even though no FT means no business for them.

The trick is to eliminate the middle man (the school) and find your own students. I pay a visa agent once a year to get a legit Z and I teach classes of 10 in my apartment, I charge my students peanuts in comparison yet I earn at least 4 times what the highest paying international schools in the country are willing to offer while teaching half as many hours. No dumb incompetent managers, no office hours Now tell me, why would I even consider working with these people?

Finding students in China is a cakewalk, print some flyers with a photo of yourself and tape them around your district, you will have more students than you can handle in no time.