Please elaborate. According to a verdict of the Federal Court for Labor from last month [1], not only is tracking an employee's presence legal, it's even mandatory as a necessary consequence of European Court of Justice verdicts. Whereas in Germany before, a trust-based system was common practice at least for white collar jobs, and only the time on top of regular contract time needed tracking AIU.
[1]: https://www.tagesschau.de/inland/arbeitszeiterfassung-stechu... (in German)