I missed this Thread yesterday.
Interesting comments.
I'll say this I defended your butt once,
don't expect me to do it again.
BTW
NEX, BX, and PX are self supporting
and I shop there just to cheat you Hawaiian Democrats
out of your GET.
To be accurate, the commissary/exchange system is a mixed bag re: self support.
In the US, that's almost true. With economies of scale, the system buys in massive quantities at equally massive discounts. Some of the costs of operations are paid in the form of "surcharges" added to the purchases -- basically a "tax" substitute.
Where we start losing money is where costs exceed revenue (duh

). in cities where family housing is inadequate on-base, military families/individuals live out on the local economy. Local civilian stores are often more convenient or offer better variety. Sometimes price is not the deciding factor when the on-base selections can't compete with online or local businesses.
The biggest issue is the overseas situation. Cost of stocking those shelves are much higher. Even though the military/families living there are more likely to shop on-base rather than the local stores, the prices are often higher then in the US exchanges. It's cheaper to order from Amazon nowadays. The exchanges are now offering online ordering, but that doesn't offer cheaper prices if Amazon isn't collecting tax at most destination locations.
As far as WHY the military has these facilities, those reasons have changed -- at least as far as US facilities. In the past, almost every military member and family lived on-base for security and job purposes. Off-base access was restricted to avoid potential problems between locals and the military. The attitudes of many civilians toward the military were much like Kukeana's -- total hatred and disdain. I'm talking decades ago -- post-Vietnam era. In order to avoid confrontations, the bases pretty much issued passes one a month on a weekend to let the troops decompress. The rest of the time, they were confined to base.
Now, there is an increasing tendency for military personnel to live off-base in private housing. Much of the Oahu military housing is built "off-base", and members have to drive to the bases they work at. Basically, military housing in integrated with the local civilian population. That includes shopping, schools, restaurants, auto repair, and every other business you can name.
Anyway, there have been studies by the DoD on making the BX/PX/Commissary systems self-supporting, and the conclusion was that the system would have to be 100% scrapped if that happens. From a purely pragmatic perspective in today's Amazon-driven consumer market, maybe it's time?