In exchange for extremely dangerous working conditions that can and usually do irreparable damage for life. It's hardly a "win" for a kid to grow up doing this for money, and have horrible health issues after the age of 30, making their remaining life miserable.
I think it depends on where in the supply chain kids are participating. If the work is dangerous (ex. mining), they should be banned but if there is a learning experience with little risk of long term negative consequences, it should be available for the interested.
I enjoyed the computer work and newspaper route I had as a child and wouldve probably jumped at the opportunity to assemble digital devices.
"This is beneficial enough that some people choose it" and "this is a genuine good thing for those people, compared to the other options" are not equivalent.