Exactly, and it also depends on the particular audience. So it's not surprising how easily such expressions can be misunderstood by non-insiders. I am not really perfect in any language, I'm afraid, let alone confident in all contexts. Sometimes I learn by mistakes (preferably other persons').

We must also distinguish between notions of politeness and the percentage of persons complying with them. The article seems to diagnose a lack of the former in German, so that Germans could not be polite even if they wanted to. As I wrote, that idea is quite absurd, and it shows how deeply some alleged scientists are caught in their own cultural mindscape.