Comment by snapplebobapple

This is incorrect. This constraint both profits off of and provides some benefit to the constrained population but it is not the source of inequality. The source of inequality is country/region level policies causing growth differences over time. The labour price spread caused by that drives the secondary arbitrage you identify above that profits the wealthy but also benefits the people living under crap government policy that caused lower produxtivity because their low wage factory job pays better than their alternatives.

constraining the labour is just a smart move when the majority of your population is a net cost to tax payers.