Americans do not tend to be as direct as Russians are
Bingo! That's it!
That's exactly what an American told me several years ago when I just started to learn English.
I guess the roots of this opinion come from the lack of knowlege of the right, roundabout English
What we learn at schools and further is just simplified, direct English.
Of course high-educated translators or like, they know the other sort of English but commonly we know only this version of the language.
So in my view, the folks just mistake language constraints for rudeness.