Oh yes using age to determine when someone can drink is discrimination! Should we abolish that and allow an 8 year old to drink? Based on your reasoning it sounds like you would be for that.
Eight-year-olds (and younger) can legally drink in restaurants in New York, provided that they are with a parent or guardian and the adult gives the drink to the child (or pours the drink the drink and gives it for the child). The child may not sit at the bar. The problem with furnishing alcohol to young children is that it's often difficult to judge how much is too much, as children have less blood volume than adults. For this reason, in England, parents require a license to furnish alcohol to their children under five years of age.