You're part of the reason that everywhere eventually ends up with ticket gates. Because people can't be trusted to do the right thing.
I wonder if there's some correlation between that kind of attitude and how the system works...
Multiple machines for different Bahn companies, zoning that's not very well explained, multiple checking machines etc...
In the Netherlands there is a single system for the entire country where you can just tap your transit or debit card and it goes.
I'll keep your tip in mind next time, though. :)
https://www.bvg.de/en/subscriptions-and-tickets/all-apps/tic...
So it doesn't really change my original point that "use an app" is not a straightforward universal answer to the complexity. If it were a trustable libre app and you squinted to ignore the table stakes inherent to any mobile computing device, that could be a different story.
Because most people have a long term ticket. (is that the correct term in English? I mean one that's valid for a week, month or year)