Actually it was common to make slaves of convicted felons right into near the end of the 20th Century.
They were used in "chain gangs" for road maintenance and other functions, and to make things in prison workshops, and grow food on prison farms.
13th Amendment: "Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction."
People have to work for their living, but prisoners don't. No wonder many of them can't wait to be sent back behind bars. There is something wrong in that.
But where do these moral principles come from? Certainly not the Bible? What other source of morality do we as a nation subscribe to?
I’d like to have a slave that’s an android robot. Just imagine: “Roby do this! Roby do that!” My robot slave would do everything, just like a butler.