It makes sense. A military is only as good as its logistics, and the US’ forward bases are the tips of very long spears, dependant on a lot of logistics. So you need to have the means to have a continuous pipeline of supplies to each outpost. In peacetime, you keep that open by supplying the troops with burgers, tacos, XBox games or whatever; if the shit does hit the fan, all that capacity can be diverted from tortillas and patties to ammunition, drones, amphibious landing craft or whatever, at short notice.
We had access to a BK at one of the FOBs I frequented in Iraq and although I've never been a huge fast food fan, that stuff was so good. It's a huge morale booster. I'm sure that sounds simplistic as fuck, but you really come to appreciate the little things when you're deployed.
Also a cinnabon. And a coffee shop called green bean. And a pizza shop. And much more. Sometimes DFACs 1 and 4 gets old.
This is serious. If the USAF sets up shop anywhere we plan on having a presence for a while, there will be some amenities. Even if the base is bombed on a regular basis.
TCNs, or third country nationals. People from neither the US or locals.
From my understanding the reason why is the almighty dollar. They don't get paid nearly as much as our troops and contractors, but still a lot more than they would make at home. There is quite a bit of info about it if you do a quick search.