Well, on that journey I had tickets for the connecting flight which was already boarding and the flight back, not to mention a paid for room in a posh hotel (in Canada) and plenty of accompanying documents from the main Canadian broadcaster. None of these documents were chewed by the dog and a sensible human being could use common sense to see that everything was legit.
However, for someone with a gun on their belt, having got their education from Hollywood films and with a government that snitches on the world to lock up dark skinned people in Guantanamo I guess this jobsworth mentality makes sense to them.
Upsetting people who have good money to spend means they don't come back. You don't want to be treated like garbage by imbeciles that insult your intelligence. It is taken personally. The U.S.A. is not that special, it is just full of entitled people that think they are special.