This doesn't pass a basic logical sniff test.
What if the private prisons provided much greater comfort, rehabilitation, medical and mental care, and so on? How could you call it immoral just for existing?
There's a country in the 30's that used misinformation to sell what you're suggesting and they, at one point, had a thriving prison system in less than a decade.
Don't be so polyannish.
SRC: https://www.ers.usda.gov/topics/food-nutrition-assistance/fo...
If you think prisons should have profit motives where growth only comes from continually seeking punitive policies to imprison people then I don't know what to tell you. The extrapolation isn't that hard and I don't see anything good coming from it. Weird takes.
Prisons don't get to sentence people, courts do.