It would be prudent if you would dig a bit deeper into how unions came to be. Long story short, capitalism can easily create situations where you agree to be exploited to some degree, to avoid being exploited to another, worse, degree.
"Agrees" is doing a lot of work in that sentence. Agreeing to $100/hour because you think it's fair and agreeing to $1/hour because you're starving may both qualify, but they're quite different.
