Again, not the best argument given that the drinking age is 21. Additionally, children can volunteer for the military at the age of 16. So there's clearly a range, "legally speaking".

Leaning on existing laws isn't really the best for these things, because existing laws may be flawed. Would prefer to base it on scientific insights, but we don't have much relevant for this stuff.

So the real answer is "We don't know, and different states will try different ages and see what sticks, what people will accept."

Florida allows 14 years old to work 15 hours.

A lot of states are removing restrictions for under 18 workers.

Also, drinking age is 21.