"Maybe it's that the first is an involuntary participation without someone's agreement, while the 2nd is someone agreeing to work under given conditions?" It's

"Maybe it's that the first is an involuntary participation without someone's agreement, while the 2nd is someone agreeing to work under given conditions?" It's an old debate, the "lochner era" debate (https://en.wikipedia.org/wiki/Lochner_era https://en.wikipedia.org/wiki/Lochner_era). "Agreeing on conditions" is not enough to make something fair. You may agree because you are desperate and you need cash, you may go straight to voluntary serfdom... Society and policy makers are fully entitled to disrupt "private contracts" when those contracts are not in line with the greater good.