Precisely. People always think they want to be "free". What they want is not "freedom" -- what they want is the right to do whatever they want whenever they want without having to worry about consequences. Not possible.
Freedom means: you are no longer bound to society's laws, nor are you protected by them. You are free. You are now bound by nature's law, and nature only has one law. You will do what needs to be done when it needs to be done...or you will die. Sickness, starvation, wild animal, exposure...nature is not going to give you a trial, and it doesn't care if you're too tired to deal with it.
Society and government are a bubble that keep nature at bay. But if you want to live in the bubble, there are going to be lots of things you need to do, even when you really, really don't want to. Fail to do so, and there will be consequences. No freeloaders. So, society is basically people giving up their "freedom" to protect themselves from nature. We all willingly enslave ourselves to the system.
"Slavery", as we use the term, means certain people are not even given the rights of other people in that society. It's wrong. It's unethical. (The abuse that occurred with America's slave trade was just atrocious.) Based on other situations, though, it's the lesser of many evils.
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We've captured a thief and a murderer. What do we do with them?
1.) Set them lose on the world again until they kill and steal from someone else?
2.) Shoot them in the back of the head?
3.) Lock them in a cell until they finally go insane and die?
4.) Put a collar on them and force them to do some work?
While all pretty awful, only one of these options results in something being built instead of destroyed.