An article in NY times tried to argue that PTSD in returning soldiers is really just lack of home support, because more are being diagnosed than actually saw enemy fire. Obviously misguided.
If you sit in a hostile foreign land where your companions are being killed, you do not have to be shot at to be traumatized. One client I had, for example, had PTSD from the Panama Canal zone even though he was never shot at. It was nevertheless disturbing on a daily basis, since his job was to go up and down the canal in the body barge collecting bodies. That picture in his head was still traumatic.
While it is true that in cultures where there is more affluence there is greater alienation and social supports are low for any problems one has, that does not account for these numbers. Some people get trauma from a car accident, or even seeing one. Should not up close and personal experience of war count as much as how many bullets one dodges? My definition of trauma is rather broad : any event(s) that exceed(s) your resources.
There are a few misdiagnoses, such as TBS being mistaken for PTSD. Not nearly so many as there were when the VA tried to mislabel for economic reasons..