Use my own case as example. My family suffered financial hardship due to some misfortune when I was 15. I really wanted to work to help my mother. There were rarely part-time jobs in my hometown in China, then. I could quit my study and try to find a full-time job, which I gave serious thoughts. I knew several people who joined workforce around that age, either due to family financial situation like mine, or they thought they had no future in school (it was already very competitive then) and it was better to work early and accumulate working experience. In this sense, they were "child" labors. But they chose to. They were not mistreated because they were under aged. In my view, they made rational decisions to join the workforce.
One of them, a classmate's brother, returned to school after working for 3 years, when their family financial turned around.
Fortunately, our family decided to open a small business. I tried to get as much time as I could to work there to help, while study hard so that I could go to the best colleges. For two years, I didn't have much time to hang out with friends. So I was a part-time "child" labor. But it was my decision. Nobody forced me. I don't regret it a bit.
Let's face the reality. There are many kids who are just not interested in school and are not good at it. There are two options. They can either hang around and be cool, which is a good situation, considering kids of that age tend to get into troubles if their minds are not occupied. Or they can get a job, learn something from the job, develop good work ethics, etc. What do you think is the better option?