There were multiple times when we were either in a park visitor center or the RV park's pool and I realized I was the only American. It was all (in order) German, Dutch, and French. Everyone was really friendly and we made some good friends at the pools. But we kept noticing all the people doing dumb stuff at the national parks weren't Americans. Feeding squirrels, flying drones, climbing on stuff that wasn't safe, etc. It kinda became a running joke.
If as you said Americans are outnumbered by European people it is not very surprising that most people spot doing silly things are European and not American ...