I'm shocked, shocked, that slave labor is permitted under Chinese constitution!
US law doesn't allow prisoners from refusing work. Penal labor is a big industry in the US. Private corporations can contract their labor jobs to penal labor where the prisoners are unpaid or paid very little (but cannot spend until they're released), and not required to provide any compensation, benefits, insurance, worker's safety, unions, etc. Slave labor essentially.
Many large corporations use penal labor, including McDonald's, Verizon, Walmart, various defense manufacturers (i.e. helmets & vests). I believe there is also a corporate tax incentive for businesses employing prisoners. Majority of prisoners are also black.. you know, the type that excell in sports and physically demanding work.
The other type of slave labor that exists in today's America are foreign contractors providing seasonal labor. Since they are not American citizens, the great Murican rights and freedoms don't apply to them, similar to but worse than the prisoners. They are commonly found working in the agricultural labor industry, usually sourced from Central America (Nicaragua, Guatemala, etc).