Fair enough. Most folks think 'Dr.' implies medical doctor. I've never taken umbrage at anybody failing to call me 'Dr.' or 'Prof.'. In fact I'm vaguely uneasy when they do use these honorifics. Most emotionally secure academics I know feel the same. https://www.npr.org/sections/ombudsman/2018/09/28/652538222/npr-doesnt-confer-dr-on-ph-d-s-here-s-why …
I worked in Munich for a year after post doc, and I'm aware the social norms are different in Germany.