This condition is subsidized by a government that neither legalizes nor protects sex workers (such as their being unbanked), and when it directs its attention to them (FOSTA/SESTA) makes their situation more difficult, rather then less, driving it farther underground.

America prefers to pretend like it doesn't see things, so it isn't expected to do anything about them. Sufficiently underground child trafficking is as good an outcome as none because how could we have known? The same way you know about any other workplace abuses; you inspect, you interview, and you make resources available. But we'd rather treat it like we treat farmwork, and simply wear blinders and continue to buy vegetables.

edit: there's no reason that providing services to sex workers has to be lead to pimping other than that we prefer it that way.