> What is slavery if not systematically, grossly under compensating someone for their work?
No, it's the notion that you have second-class citizens or even non-citizens with limited legal rights enforced by the state, said limitations usually being in the realm of property rights, personal freedoms, etc. At least that is fairly easy to define, whereas "grossly under compensating someone" is a vastly more nebulous term (who decides what is and isn't "under-compensating"?)
No, it's the notion that you have second-class citizens or even non-citizens with limited legal rights enforced by the state, said limitations usually being in the realm of property rights, personal freedoms, etc. At least that is fairly easy to define, whereas "grossly under compensating someone" is a vastly more nebulous term (who decides what is and isn't "under-compensating"?)