Please don't go down this line of reasoning. I think we all understand that a family run farm or shop is going to have their children work there at some point. This is not a problem because the parents (usually) have a vested interest in their children's health.

However children working on farms loop hole is rife with abuse: https://www.hrw.org/news/2018/12/04/more-us-child-workers-di...

The reasons why we have prohibitions on child labor in general is exactly the problem noted in the OP. Desperate parents will essentially put their kids at risk (even sell them) and unscrupulous employers will abuse children.