Different states have different laws. In California, the age for drinking alcoholic beverages is 21.

AA has established policies that may supersede state policies, but provide them with some mitigation of liabilities, I suspect. Ergo, Flagship Loinges with self-service alcoholic beverages have the 21 years of age admission policy.

At Admirals Clubs you ask the bar keep for alcoholic beverages; that person would be responsible for checking clients meet the state requirements. But there’s an 18 year old threshold for Membership or admission.