I believe it's still there overseas to match the drinking age in the host country.
It's less a matter of the military trying to be fair and more an issue of practicality: if the servicemen can simply go off base and legally drink anywhere they want, it will just clog the military legal system up with alcohol-related charges for something that would be legal for anyone other than the US servicemen.
There actually used to be an exemption to the drinking age for active servicemen. Not sure if there still is.
I believe it's still there overseas to match the drinking age in the host country.
It's less a matter of the military trying to be fair and more an issue of practicality: if the servicemen can simply go off base and legally drink anywhere they want, it will just clog the military legal system up with alcohol-related charges for something that would be legal for anyone other than the US servicemen.