You're viewing the dynamics of the conversation much differently than I am. I'm saying that it's clearly wrong to sell children into prostitution, due to the empathy we all seem to share for our fellow human beings. The (clear) existence of that empathy is enough to justify the statement that such behavior is "wrong."

You then ask me to explain where that empathy comes from. I don't know, and I don't particularly care. The fact is it's here. We don't need to know "why" it's here to know that it's here.