You are missing the point - the rudeness we are talking about here is omission rather than commission; the "me, me" attitude manifested by the lack of consideration for anything around "me" and dumping "my" shit on them (noise, trash, dog poop, pollution, etc.), the expectations that everyone should speak English, even in a foreign country, and serve "me," the sense of entitlement to get anything 'I' want and getting pissed when 'I" do not get it, and a general lack of interest in anything that does not directly pertain to "me."
People may be superficially polite in a small talk way, by saying the right magic words, yet they are perceived as "rude" if their general attitude is disrespectful of others. Americans tend to be disrespectful of "others" be it people form different countries, different political camps, or simply people other than themselves. I think many foreign cultures have a very keen sense of that, and that is why they consider Americans "rude" even though only superficially "polite" words are uttered.
Wojtek