A Japanese friend told me that expatriate workers in Japan are paid differently depending on where they came from. For example, professionals from Europe and North America are paid more than professionals from other countries outside Japan, even for the same job. Of course I don't know if that is true, and I don't have the statistics to back it up.
But my friend's comment perked my interest because this isn't the first time I've heard of stuff like that. I read that in some of the Arab/West Asian countries, they pay Africans and Indians less than Europeans in the same professions. I also heard about similar patterns in Southeast Asia - Indians and Chinese expatriates are paid less than European/North American expatriates.