"Digital-only" = By smartphone app OR by smartcard, i.e. a card like a credit card with a chip and your personal unique ID stored on that.
In other words: You cannot get a plain old paper ticket without personal information, the ticket is like a cookie which identifies you as a user and thus allows you to be tracked.
In other words: You cannot get a plain old paper ticket without personal information, the ticket is like a cookie which identifies you as a user and thus allows you to be tracked.
Disclaimer: Not a resident of Germany.