Robin Hanson has an excellent post on child labor that co-blogger Bryan Caplan has cited. I think Robin doesn't go far enough, though, in one respect. He points out that tiger moms often force their kids to do things that, to us great unwashed, look a lot like child labor, but without pay. He doesn't emphasize, although he briefly mentions, that children are forced to go to school. In other words, school goes beyond child labor. It is forced child labor.
It reminds me of a story I read in Reader's Digest when I was a kid. A child was asked, after his first day of school, what he thought of school. "It's alright," he said, "but it's sure going to cut into my day."
Robin emphasizes correctly that the objection to child labor seems to be based mainly on the idea that the child is making money. One of his critical commenters points out that there is still a lot of child labor on family farms. Most of that is not paid for. I remember when I was a teenager in a school in the farm belt of Canada, some of my teenage colleagues (some as young as 13) not showing up for school in September and early October because they were driving trucks and tractors during the harvest. I asked them about it and one kid told me that he was driving a tractor in the summer as early as age 9.
So my conclusion is that the law against child labor is really a law against children making money. Thanks, government.