Trafficking vs Migrant Labour

I have been thinking of the difference between migrant labour and forced labour as it pertains to the sex industry and to agriculture. In both cases I think there are more migrant workers than trafficked workers, but the discourse is never framed that way. Working conditions are never addressed. The Asian micros in Canada for example are filled with women who chose to come here to work, but have no say in the working conditions. And as for agriculture, I have been thinking how badly we in the United States and Canada need those migrant labourers in agriculture to survive. We truly feed ourselves at their hands, but set things up so they have no rights. Even when we shop and eat local. It astounds me. Where is the public discourse on these issues? Send me links. I need to learn more.