If a US person made those "Now, I am fully aware" comments you quoted, I think one likely interpretation is that they are generalizing from anecdotes from personal experience (possibly including conflating distinct properties), and resent that.
Another possibility is that, although the English is excellent, there are probably implicit cultural values and ideas that are unfamiliar to me.
(Incidentally, though I don't think it's the case here, I've also sometimes seen tone like that slip in when someone is astroturfing, or writing a persuasive piece around misrepresenting their real position, but is not good at it. It's a bit like Fellow Kids.)
Another possibility is that, although the English is excellent, there are probably implicit cultural values and ideas that are unfamiliar to me.
(Incidentally, though I don't think it's the case here, I've also sometimes seen tone like that slip in when someone is astroturfing, or writing a persuasive piece around misrepresenting their real position, but is not good at it. It's a bit like Fellow Kids.)