I think one of the things driving patronage at, at least, the enlisted clubs is the drinking age laws. Ages ago, the base commanding officer set the limit, usually 18. When that was changed, the new military-wide rule was 21 on base or whatever the lower age limit was for another jurisdiction (including a foreign country) in which the base is located or within, IIRC 50 miles of the base*. Finally, the regulation, which is still in effect, is 21 regardless of the drinking age nearby. For example, in South Korea, the drinking age is, effectively, 19, while on base, it’s still 21 years. That leads to some really stellar examples of bad planning. 18, 19, and 20 year old soldiers will get drunk off base and then stagger on base, getting into trouble with the military for something that’s not illegal in the community and the staggering soldier could’ve checked into a hotel and returned to base the next morning sober with no problem.
*While I was in, some of my friends and I were joking around one night about what other age-restricted laws or what other laws in the US should be subject to this “nearby jurisdiction” exemption. I think we got the list up to about a hundred until we got bored with it and went on to another party game.