Jeffrey Tucker offers an interesting perspective on child labor laws:

Let's say you want your computer fixed or your software explained. You can shell out big bucks to the Geek Squad, or you can ask — but you can't hire — a typical teenager, or even a preteen. Their experience with computers and the online world is vastly superior to that of most people over the age of 30. From the point of view of online technology, it is the young who rule. And yet they are professionally powerless: they are forbidden by law from earning wages from their expertise.

Might these folks have something to offer the workplace? And might the young benefit from a bit of early work experience, too? Perhaps — but we'll never know, thanks to antiquated federal, state, and local laws that make it a crime to hire a kid.
. . .

By the time this legislation passed . . . it was mostly a symbol, a classic case of Washington chasing a trend in order to take credit for it. Youth labor was expected in the 17th and 18th centuries — even welcome, since remunerative work opportunities were newly present. But as prosperity grew with the advance of commerce, more kids left the workforce. By 1930, only 6.4 percent of kids between the ages of 10 and 15 were actually employed, and 3 out of 4 of those were in agriculture.

The first advocates of keeping kids out of factories were women's labor unions, who didn't appreciate the low-wage competition. And true to form, labor unions have been reliable exclusionists ever since.

Opposition did not consist of mining companies looking for cheap labor, but rather parents and clergy alarmed that a law against child labor would be a blow against freedom. They predicted that it would amount to the nationalization of children, which is to say that the government rather than the parents or the child would emerge as the final authority and locus of decision-making. To give you a flavor of the opposition, consider this funny "Beatitude" read by Congressman Fritz G. Lanham of Texas on the US House floor in 1924, as a point of opposition to a child-labor ban then being considered:

Consider the Federal agent in the field; he toils not, nor does he spin; and yet I say unto you that even Solomon in all his populous household was not arrayed with powers like one of these.

Children, obey your agents from Washington, for this is right.

Honor thy father and thy mother, for the Government has created them but a little lower than the Federal agent. Love, honor, and disobey them.

Whatsoever thy hand findeth to do, tell it to thy father and mother and let them do it.

Six days shalt thou do all thy rest, and on the seventh day thy parents shall rest with thee.

Go to the bureau officer, thou sluggard; consider his ways and be idle.

Toil, thou farmer's wife; thou shalt have no servant in thy house, nor let thy children help thee.

And all thy children shall be taught of the Federal agent, and great shall be the peace of thy children.

Thy children shall rise up and call the Federal agent blessed.