re: Again, the critical word is "voluntary."
As long as hiring a new employee at the same salary is easier than finding a new job at the same salary, there's nothing voluntary or free about it. It's coercion.
I'm practical enough to understand this is how the world works, but don't expect me to get all misty and fluttery about it. The relationship between worker and employer is adversarial, as is the one between buyer and seller. I may have no choice about living in that kind of world, and I might even be clever enough to prosper in it, but I have no illusions about what really drives it: violence.