(FORTUNE Magazine) – Some years back we took an IQ test (don't ask why). One section was designed to elicit information about one's common-sense understanding of various phenomena in everyday life. Among the questions in this section: ''Why are child labor laws necessary?'' Our argumentative answer was that, in fact, they are not necessary and probably do more harm than good. Luckily the tester was an amiable chap who agreed to settle for a statement about the theory behind the laws, and marked us correct for stating that society wants kids in school. The episode bounced back into memory recently as we waded through a barrage of news stories about presumably god-awful violations of child labor laws. The Burger King chain is paying a $500,000 fine to settle a child labor case brought against it by the U.S. Department of Labor. An AP story tells us that ''child advocates'' say violations are rampant. One of the advocates, Jeffrey Newman of the National Child Labor Committee, says violations today are at a far higher level than in the 1920s. Actually, the answer we gave the tester was incomplete. The high-minded theory behind child labor laws is that kids belong in school, but the driving force behind legislation is that the laws will reduce job competition faced by adults. When restrictions on child labor were put into the Fair Labor Standards Act in 1938, the national unemployment rate was 19%. The law today states that kids under 14 may not be employed in interstate commerce, that those under 16 may not work more than 18 hours a week when school is in session, and that 16- and 17-year-olds are forbidden to work with some kinds of machinery. But wait. Don't we want our kids to be spending these years on education rather than flipping hamburgers? Well, sure, but almost all states have laws requiring school attendance, so what is gained by restricting their job opportunities? You worry that they won't get enough sleep? Or do enough homework? But these should be the parents' concerns, not those of politicians egged on by unions. Or, rather, they should be the joint concerns of the kids and their parents. The parents will often quite properly see the jobs as a useful introduction to the labor markets. The kids will typically see the jobs as the best available way of getting the cars they long for. Both will be correct, of course, though you would never know it from the press. Or the IQ tests.