If you think about an agricultural economy centered around a cash crop for export—it could be cotton, coffee, or whatever else you like—then realistically locally focused food production is also going to be part of the picture. The cotton farmers need food after all. So you could easily have a situation in which a bunch of farmers are clustered in a village, partially growing vegetables for basically their own consumption and partially growing cotton. In the unfair trade paradigm, children and adults alike grow both cotton and vegetables. Then when you switch to a fair trade paradigm, what you get is labor market segmentation. Maybe children stop working in the export-oriented cotton fields, but now children are doing all the vegetable farming. The household- and village-level economies, however, are still dependent on child labor. This is all just very tricky to deal with unless the country where it’s happening has the state capacity to enact mandatory free public schooling rules and enforce them effectively as a matter of policy.