Let's take these one at a time. As an anarchist I am against government laws of any kind. But I don't get to live in the environment I prefer. You're concerned about child labor laws. Can you define what labor should be allowed and what should not? Is a kid mowing lawns in the heat of summer covered by such laws? If not, why not? Who gets to decide what is permitted and what is not? Government bureaucrats? I would not be in favor of child labor laws under that circumstance, any more than I favor government bureaucrats deciding which light bulbs I can buy or how much water pressure I should be allowed. That does not mean I want children to be performing work that is dangerous to them, and I would shun (and advise everyone within earshot to do the same) anyone who put his or her profit above the safety of a child. I am against government bureaucrats deciding what work a child can do and what is forbidden. Obviously, we disagree.
Sex trafficking is an animal with a different stripe. A society of free individual precludes anyone being a slave forced to perform sexual acts against his or her will. So, yes, considering the world in which I live, one with a government, the government being the entity that defends liberty, sexual slave trafficking is something a government should banish.
I hope that clarifies for you what you were looking for.