Capitalism did not create child labor working in fields or factories, but inherited child labor from the previous political systems.
Observe in communist Cuba of the 70s/80s, 11-year-old children are forcibly sent off to “summer camps” where they spend time working in fields cutting sugar cane and tobacco (and if the girls are pretty they get to spend mandatory time with older communist officials.) This is called “volunteerism” (and the joy of women under communism) by collectivists.
Children working in factories was only a transitory stage between early feudalism and capitalism.
Before working in factories, before capitalism, many of children had shorter lifespans. The evidence of this is population and infant mortality statistics: population did not go up, and infant mortality did not go down, until the Industrial Revolution. If life was so great before capitalism in the “country,” why was infant mortality so high and population numbers considerably lower before capitalism? Answer: life was not so great until Capitalism.
Throughout history, parents could not produce enough to support their families without having their children work also. It was the accumulation of capital by the industrialists that increased the productivity of adults so that children did not have to work in fields or factories. In poor non-capitalist countries, they are still working in fields because the parents are not productive enough to support their children. As economies are becoming freer, thankfully this situation is changing.
Contrary to the anti-capitalist rhetoric passing child labor laws in these third-world countries will not solve the problem, but will only lead to a lower quality of life and possible starvation — which is why the “poor” themselves resist such laws.