Adults paid minimum wage without other sources of income are poor. What you’re implying is a system that pays children a living wage that is above the current minimum wage. What employer is going to pay someone more than minimum when they are a child who will have major limitations and liabilities as an employee, and when they could potentially pay a full grown adult to do more work with less liability for less pay?
The only reality where that happens is when it is a job that a child can do more easily than a full sized adult, and that is exactly the kind of work that made child labor illegal in the first place—those little hands can sure reach deep into those factory machines, can’t they?