I suspect you mean "beneficiaries," and you're right to point this out. It is appalling that slave labor apparently wasn't enough of an immoral business advantage for them.
> The 13th Amendment made chattel slavery and involuntary servitude unconstitutional, yet it included an insidious exception: “Except as a punishment for a crime.” This simple exception means instead of eliminating slavery, the 13th Amendment, ironically, extended it into perpetuity.
https://www.google.com/search?client=firefox-b-e&q=slavery+u...