[edit: As pointed out by various commenters below, some of these might not be technically true, or have outs, such as being able to go back home to show your ID. My hypothesis is that common official workflows lead to these perceptions from the outside, e.g. As a foreigner in a country, if an official asks you "Where is your anmeldung?", you are not very likely to challenge them back and say "Actually, it's not required, please use the workflow that allows for absence of one."]
- You have to register your current address with the local authorities (anmeldung) after moving into a new place. By itself this seems fine, but it also seems to bea prerequisite for a lot of life necessities like getting health insurance and a mobile phone number.
- If you are in Germany and run a website, you need to have an Impressum on your website that states your address. So you are pretty much auto-doxxed every time you decide to maintain a personal website or blog. I am not sure how much this is enforced.
- There is a "Stop and Identify" law (Personalausweisgesetz) that requires you to be in possession of an identity document, and hand it over when asked to by any authorities, with substantial fines for noncompliance.
- From my own experience as a visitor, Wi-Fi portals always seem to have a great deal of personal data entry before you can get on the Internet. Apparently there were previously laws that put a great deal of liability on whoever ran a Wi-Fi network, which meant that businesses were naturally loathe to offer one.
It would be interesting to me as well to hear from Germans who grew up with these, and how they perceive their impact on privacy.