However, the countries you mentioned do not speak with a western English accent, which the market calls for.

Please keep in mind that caucasion people from Scotland, Ireland and South Africa have a difficult time finding a teaching job in China as well.

What about Jamaicans?

As well, how many Nigerian teachers are teaching in Korea or Japan?

Why are they not screaming about not being able to get a job there either? What makes China so horrid for only hiring people with the desired accent?

Think of it from their perspective. They want to learn English so they can talk just like a native English speaker. They want to learn this English so they can go to America, England, Canada or Australia. How many Chinese immigrants are there in Nigeria? So why would they want to learn that accent?

What about culture? A foreign English teacher comes here not only to teach their language but their culture as well! The Chinese students want to know everything about the culture differences between America and China. I'm a Canadian. The students don't give a rats ass about Canadian culture. As far as they are concerned I'm an American. ( snarl ) But my culture is similar enough to American culture that I am able to teach it as simply Western Culture.
Nigeria and the Phillipines are not considered "Western Culture".

They want English from First World Countries so that they can go there.