I do not find it strange or otherwise see it as a loophole that duly convicted prisoners pay some of their debt to society by being forced to do labor.
It at least hinges on what people are convicted of being things that "deserve" slavery. Not all agree that possession of drugs for personal use meets that. Or performing or having an abortion. What if the government turns full Russia and makes political dissent illegal? Or championing/practicing "non traditional family values" like LGBT?
There is also a moral hazard in being able to earn money on prison labor, as it incentives putting people in prison.
I agree that the moral hazard is there, and it's fraught with potential for abuse[0]. But prison labor also has the potential to teach convicts skills and discipline that would be useful after their sentence.
> Not all agree that possession of drugs for personal use meets that. [...]
I'm not sure if you're saying that there is disagreement in society about what things constitute crimes, or that there should be a difference in how we treat convicted prisoners on what they were convicted on?
On its face, I'm not sure why, say, someone convicted of manslaughter is "deserving" of being made to do labor and someone convicted of, say, felony reckless driving is not, or vice versa. But I'm sure there are arguments to be made in either case.
[0]: Like the "Kids for cash" scandal in Pennsylvania, though I'm not sure if there was a labor component involved there and not just a per-prisoner payment (which is just as bad).
The vast majority of slavery historically is this. While I can't say I disagree with you, it's also awkward because you must then conclude that the vast majority of slavery historically was "okay"/"justified". Clearly some subjectivity and subtlety is needed.
