As is quite evident, Qatar finds no need to have a mix of nationalities for positions such as domestics or labourers. Yes, there are folks employed in these positions in Europe/USA.

If an employer is paying 2 or three times the wage to an European/American to perform the same job as an Asian, its not simple arithmetic, its discrimination. Why is a European worth more? Yes, he won't come to Doha for the same salary as the Asian. So be it. Let him stay put.