> Child labor just disappeared on it's own right?

No. It took capitalism—more precisely, the resulting accumulation of human wealth and technology—for child labor to disappear. It disappeared when it became economically unnecessary for children to work:

http://atlanticsentinel.com/2011/01/did-government-end-child...

I am continually surprised by the number of people who seem to be under the impression that the default state of nature is one of abundance rather than scarcity. Why do you think children had to work in the first place?