Why? FT is international, as is airline travel. I can recall many stories on FT over the years involving upcharge and/or threat of arrest, including at least one which I reported. I vaguely recall a LH arrest at FRA or perhaps MUC from a few years ago reported by another poster. Searching the web in various languages would I'm sure bring up examples, besides the very few I posted here.

But it's past my bedtime, so I'll leave that for another day, or to another poster. But it definitely is not unheard of, as people have reported here (both passengers and crew)