This is not what the grandparent is saying. The typical situation is not that people are forced to do the work. We're not talking about slavery* here.

They are doing it because they see it as their "best option". By stopping it, the result is their "best option" is taken away from them, and they have to go do the next "best option". You could keep saying "this is inhuman, let's stop it from happening", but the effect is just making it worse and worse. Instead, better options should be provided. That's the real solution, but it's a whole lot harder to implement than the knee jerk response of stopping an activity.

edit to preempt ridiculous interpretations of my words: This is assuming slavery is not the case. If slavery is involved, it is a different situation to what i am talking about.