It's not just German trains. The Swiss are rather strict about train punctuality (more than 2 min is not accepted if memory serves), and if an international train would cause delays, the Swiss put on their own train on regular schedule and halt the tardy train at the border.
[0]: https://company.sbb.ch/en/the-company/responsibility-society...
You're dealing with a bunch of people who will try to rip you off, so you need to have anti-fraud protections. Then you need to be able to override the anti-fraud protections because Alex, Alex and Bob, Alex, Bob, and Curt, etc. are all legit performers who want the payments to go to one common bank account even though you'd like one act == one bank account. Etc.