The North has appropriated labour from outside, but also within: undocumented workers work for less. Also the worker's education and care is paid for by the country of origin, the recipients profit from it for free
I also think that colony, by amplifying corruption and inequality actually hinders the economies it parasites, lowers outputs.
The strategy to stop making things and living off of rents, IP enclosure and plunder will backfire badly as the south finally gets rid of colony