(USA centric view) You cannot legislate parents into being good parents. You cannot pass laws that protect children from bad parenting as best case result you may get the state to intervene and put the child in a foster system where there's a 50% chance that they end up in an even worse place.
Laws against child labor might be an example most of us would agree are called for, instead of just leaving it up to the parents whether children should work in mines and sweatshops or not.
Although I have no doubt someone will show up and say that should be left up to parents too.
Children have assisted their parents in their work as they are able from an early age for millennia. It serves to train them in useful skills they will need as adults and also to improve the family's financial prospects, which is beneficial to the entire family including the child. Increasing wealth, in some areas, has allowed for the luxury of allowing children to prepare for adulthood in less immediately productive ways, such as schooling—but that does not imply that it is wrong for children to work. Most parents care deeply for their children's welfare; in general you can trust that if parents are asking their children to work they are doing so for the children's benefit. If you would prefer that they didn't need to work the solution is to offer them a better option, not take away one of the few ways they have to improve their situation.
