The legal restriction needs to be very specific and demonstrate a good trade-off between societal gain and harms on the individual's right, not something a clean cut like many folks misunderstand.

Alcohol and Tobacco are pretty straightforward in the public health context. And you probably don't want your toddlers to drive a car given the risk. The voting age is an exception as it's defined in the 26th amendment. I consider it as political compromise though.