So there is a book called IQBAL, a children's book about a real boy in Pakistan who is a child laborer. My kids read it when they were perhaps 4th or 5th grade. Some of it is upsetting (he is not well-treated), but it is meant for children and so the level of storytelling is fairly mild, given the very serious topic. Kudos to your dc -- she is trying to understand the world. Her comment about being a better person is wonderful.

One of my dc's has this social-justice edge too.