In todays litigious USA, children would come with too much liability to employ in many many settings. Children are quite capable of doing many different jobs. Total exclusion from the workplace delays the earnings, experience, learning, and networking of people.
Child labor laws have made exceptions for performers for some reason. I think most people would agree that this is fine. Why have we not made exceptions for other areas of work?
A less regulated child labor market would find those exceptions naturally.