I agree with Reno and Raoul, a lot of teachers are spineless and the bosses know it, see it.

I just got a call from a 51 year old American woman in China and she says because her 11 classes a week at a Middle School are too crowded (50+/class) management wants her to teach 22 classes next term with no mention so far of more pay or a new contract. She is stressed out and venting to me on the phone but is telling me she "will probably do it because the students like her so much." This is so soft in the head.
People who get abused are usually not masocists, they just don't have the courage to stand up for themselves. They wimp out and swallow their anger. I make it clear I don't get pushed around, so I usually teach at schools just one year. I don't mind this as I know it is the best way and I see more of the world. Why do people keep teaching if they are not paid? Go to a store and you will see the law of the business jungle: No cash = no goods or services.
Why did that guy Mike keep taking jobs in Russian if it is corrupt there and he did not get paid? I guess he finally had enough.