Foraging (or farming, hunting, etc) is involuntary. Nature has compulsive power via biological needs and imperatives.
The difference lies in the fundamental difference between natural law and synthetic human systems. Entropy isn't your master, it's a fact of your own existence.
By contrast, the present economic system is a synthetic construct made by other humans to exploit you, designed with largely that purpose, co-opting your biological needs for coercive power, and doesn't necessarily need to happen.
That's what makes one slavery and the other not.
The difference is so obvious, I actually am confused why you think conflating physics with political norms was appropriate.