If the USA reformed its immigration laws to include an actually functional guest worker program, most of this problem would go away. We did have one, at one time.
Think about it. Temporary farm workers would come in via permit from Mexico, Guatemala, and other countries. They work legally, the government would know they are here, and unscrupulous farmers and factory owners wouldn't be able to pay them sub-minimum wage or force them to work in unlawfully dangerous conditions. They wouldn't be afraid of deportation because they would be here legally, doing the jobs they came here to do, and would have access to legal recourse for violations of their rights. When the work is finished, the workers return to their home countries with the money they've made, where the U.S. dollar will go further, and (hopefully) invest in their home countries' economies.
We get the labor we need (which is unavailable here), and the workers get the fair treatment they deserve. Two birds with one stone.
Add this to the ever-expanding list of "things the U.S. Government should be doing, but isn't".