I have never said the difference in pay for different nationalities is right, and all along I have said it is discriminatory. What I was having issue with was your line of argument in relation to the difference in someones home country of the value of the money they are paid here. If you are not saving a nest egg here in the UAE what the hell are you doing here, I mean come on, who would choose to live in Dubai and put up with the traffic/building chaos if it wasn't for financial reasons. So I will say again the vast majority of people are here to save for the future back at home so what their salary is worth back home is the number one consideration for a new hire. The first thing everyone does is convert the salary on offer back into their home currency and then compares it to their take home pay at home and compare their bottom line and in a large way this decides if they will come here.
I'll say again just so you don't miss it, I don't think the system of paying different salaries for different nationalities is fair or right, but it is a fact of life in the Middle East. Also I will say again for your benefit, the 100 USD example is extremely pertinent, because the bottom line to all this is, the value of a dollar is not the same for everybody. Whereas in Australia you need to save at least $300,000 USD to own a decent home in a major city in Australia (minimum), you will get yourself a palace in a lot of Asian countries for a tenth of that. Yes while you are in the UAE your cost of living will be the same no matter your nationality, but (and listen carefully because this a big but), if after spending that same amount of money, the Australian will have $100 USD left to save he will not take the job, whereas maybe for a Sri Lankan, or a Pakistani, that $100 USD savings will be enough to make the move worthwhile.
This is going to be my last attempt to explain this concept, as it doesn't seem to sink in.