Why not a change in child labor laws?

I answered a question about parenting involvement, and how that may have changed over the decades. I mentioned a change in labor laws. I have had some interesting discussions with friends on the topic. Some think it would be hideous. Some like me, think that it could be a very good thing for some.
When Robert Blake was four, he auditioned all by himself for show business. Other enterprising children have sold produce, shined shoes, delivered newspapers.
With what seems an ever growing population of uninvolved parents, and laws which have been revised numerous times to make work conditions improved; why not?
I am not suggesting sweatshop conditions. I mean employment in an environment which would suit. Children could not be air traffic controllers, or welders, or work twenty stories up building skyscrapers, duh.
What are your opinions? How long ago were various child labor laws enacted, and what/when were other laws regarding work environment enacted?
Could it be done? Should it?
People outside the US, please weigh in, and discuss what child labor laws exist in your country. Does child employment work well anywhere now?