I am surprised that age restrictions are so stringent in China. In Canada children can legally work at 12 in many provinces and some work who are younger for actual companies and agencies in year round positions.
They must also go to school of course.
Not sure if this is good or bad as I have known some straight A students who have worked more than 20 hours a week year round and it seems to be by choice, not necessity.
National Labour laws are pretty strong in Canada but illegal practices are still common enough that it can take months to process a claim for unpaid wages, and longer to collect them as it often has to go through the Supreme Court.
I feel that it is naive to think that child labourers, legal or not are never abused even in big companies with strong policies against such practices in any country.