True, but whether inmates are forced to provide cheap labor still makes a lot of difference. After the abolition of slavery in the US, prison labor has been used as a replacement in areas that used to rely on slave labor.

> whether inmates are forced to provide cheap labor still makes a lot of difference

What is 'force' though? "Do this or I hit you with a stick"? "Do this and you go back to your cage"? "Do this or there will be nothing positive in your life"?

The prison gets cheap labour. Slavery is just a border on a map of human exploitation, I think some distinctions need far more qualification to be relevant.