

Our (privatized) mail service offers an identification process to third parties where you either walk into a post office with your physical ID card or you make a video call with a call center and show it to them. I don’t think they transmit any more data than “over 18 yes/no”. So while data hording might often be the reason, I don’t think it’s the only one ¯\_(ツ)_/¯
Fun fact: Einwohnermeldeamt is the shortest German word beside “Ja”, “Nein” and “Wadenbeinfraktur”