Worker pay will not go up with unionization if there is not a somewhat tight labor market with that skillset. Otherwise the employer can just layoff everyone in the union and start with unencumbered employees elsewhere.
Social security, workplace safety, overtime ... all just magically appeared, correct?
Because maybe, again, just maybe, I'm being dense, but I don't think "skillsets" were ever a limiting factor for those who spearheaded unionization. "skillsets" are a facet of the bourgeoisie labor market, which I say as a firm capitalist. It's always been those at the bottom who have fought for worker's rights.
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?