I'm really quite reluctant to deny my life experiences up til now on your word, telling me they've been wrong experiences. I'd guess we've just seen different things out in the world.
I don't think we are, since the region you claim the behavior generalizes too is the one I am also most familiar with. I think you are simply making the mistake of confusing "a person's preferred appellation, which is sometimes their legal first name but very often something either subtly [as in shortened form] or radically different from.the first name" with simply "first name".