Think about any other item that has an age restriction to purchase, but not "use".
Children cannot go and get their own prescriptions filled, but they have prescriptions written for them and handed to their parents or legal guardians. obviously the children will "touch: the prescription medicine, but they generally do not carry the bottle of medicine around with them. Obvious exceptions include asthma inhalers, but for those emergency injections, they are in the possession of school teachers or nurses.
Booze is illegal for children to use - period. Very different from the RMS regulations which only apply to purchasing and safeguarding.
-Fred Shecter NAR 20117