Why in some no.1 countries construction workers and domestic workers are paid very low as $10 per day..?

Question

Regardless of their hard work and contribution to the economy in nation building, any organisation looking into this disparity..

Answer 1

in south africa we pay the construction workers 80 rand a day, this is about 12Us dollars. but if you work in the upper class areas you get paid 3000rand a month with your food, water, electricity and housing for free. this is about 430Us dollars.