Sorry, I dont agree with that it depends on Exchange rate, its purely depends on Nationality, the westerns & locals life style is different than the asian, basically the asians are tend to adjust with whatever available, and they spend depends on their income, more over there are many asians are unemployed back home and hard to earn even $100 a month, so the companies or the sponsors are taking that advantage and paying less. However, you can always demand more or in conjunction with other nationalities, if they dont agree don't accept the offer. The choice is always ours. Finally there are no obligations to the company that they should pay everyone as same nor we have any right to ask.
Thanks