I don't know how you travel but Europeans love me. More hospitable and welcoming than Americans for the most part.
Most of the people I met in Europe were very nice to me. Especially the English, French, and Spanish. The Italians and Germans were a bit less courteous, but nothing terrible. The French were, by far, some of the nicest people I’ve ever met. Not sure why they get a bad rep.
My experiences have come from being apart of the US Navy. The Turks and the Italians were mostly rude. Cypriots, Portuguese and Spanish were ok. Most of them want your money and want you to leave. The Greeks were nice. Never been to Germany, France or wherever this coach was from though. I just don't like that he called out one of Germanys best ever players son and basically said his problem was that he was part American.
The guy who said that is Hungarian and grew up behind the Iron curtain. Most German coaches like the American players`mentality - it is always mentioned in a positive way, when they talk to the German media about players such as Pulisic or McKennie.
Yea, like that son doesn't have other issues. And about "one of the best ever" it depends how many "best evers" are on the list. https://www.101greatgoals.com/blog/bild-list-the-100-best-german-bundesliga-player-of-all-time/
The quote was about his work ethic but you can talk about him needing to work on things without saying that it's because he too American. That list is specifically about Germans in the Bundesliga, of which he won the league and the Europa League, but looking at his international career he medaled at the Olympics, won the Euros and a World Cup. It's a pretty impressive list. I didn't care for JK as US manager after the '15 Gold Cup but I'm not going to down play his playing career because of it.