Actually, some contempt of servicemen and women did occur during Vietnam era in the US.
When I was stationed in Rantoul, IL, I took a weekend pass to Chicago. The first hotel we tried to register at, turned my buddy and I down. Although, in fairness, I think it was because we were very young, without credit, and with barely enough cash to pay for the room. It was soon forgotten though after an hour in a certain part of downtown.
On the flip side, I spent St Pat's day at a bar in LA, in uniform and every hippy and dippy civilian bought me a round that night. I guess on that night we're all Irish.