I suppose that this has been a thing since foreign garrisons were a thing. But it seems to be one hell of a thing on Okinawa & points East generally:
The U.S. Department of Defense keeps alcohol plentiful and cheap on Asian bases, too. For example, a shoppette at Yokota Air Base was recently selling a 30-pack of Miller Lite beer for $12.99. By comparison, a six-pack of Budweiser would have cost the equivalent of about $15 at a nearby off-base Japanese supermarket.
Shoppettes also stock the super-cheap Military Special brand of spirits. A 1-liter bottle of Military Special tequila costs about $10 at Yokota’s shops.
It's amazing how you can maintain a forward military policy on the supposed premise of mutual respect, joint interest and general alliance and then funnel cheap rotgut to Our Boys: empire and capitalism in a one litre bucket. But I suppose that's as old as foreign garrisons, too. Also, credit to Stars and Stripes for running a Bad Behaviour in the Pacific page, I guess.