Child labor is illegal in the US because of a movement fueled mainly by women: specifically: mothers — frank
Later you said you have moved on. Fine, but I want to put in this argument against child labor:
One of the tasks with which people are burdened is "the reproduction of society":
IF the next 50 years were going to be exactly like the last 50 years, child labor would not be a problem. Children born into drudgery would just continue in drudgery, century after century. Child labor would be good preparation for adult life. As it happens, though, the last 50 years hasn't been like the next 50 years for several centuries. Nature will reliably produce new bodies, but it takes nurture to produce people fit to operate a society in which change is on-going.
The upper and ruling classes have always educated their children, because their children needed to be able to manage estates, climb the various hierarchies (church, state, empire, etc.), manage people, be literate to some degree, know how to behave toward their betters and lessers, and so forth. Common labourers didn't need this sort of education, because, as
a rule, they were not going
to rule.
But in the latter part of the 19th century, it became clear enough to enough people (mothers, among others) that children were going to work at jobs their fathers had not done, in a society that might be quite different than the one in which the parents had been born into. Hence, child education.
Initially, public education (as the term is used in the US) had a fairly high toned quality. Latin was commonly taught in public schools into the 1950s (and in some schools longer). The curriculum served the liberal arts. (Some schools taught trades).
After WWII, to pick a handy watershed, schools began educating children to fit into a more highly commercialised, corporate dominated economy. Liberal arts remained, but there was a greater emphasis than before on one's role as a consumer, as well as being an employee who behaved properly.
By the late 1970s into the 1980s, the role of consumer became paramount (for the masses) and the means to educate children about how to serve as a consumer 24/7 were available: TV, radio, movies, magazines, recordings, and so forth. For many students, education could (sort of) leave school and be conducted at the Mall and by watching TV. Later, the Internet would add another avenue of training outside of the red brick school. (Actually, little red brick school houses went out with 78 rpm records to be replaced by terrazzo, glass, and brushed aluminium).
Mothers were on the right side of history (to borrow a phrase) but history was pushing them along.