I am meanwhile getting attacked for this blog post https://jonworth.eu/one-ticket-or-more-than-one-ticket-for-my-international-train-trip-more-than-one-with-passenger-rights-is-the-simpler-solution/
"Passegers want one ticket!"
Sure it'd be nicer.
But if the European Commission wants to try to legislate to get hundreds of rail firms to collaborate to get to one ticket, THEY WILL FAIL, because RAIL FIRMS are the strongest lobbyists, and they sure as hell don't want it. We passengers are nowhere.

One ticket, or more than one ticket, for my international train trip? More than one, with passenger rights, is the simpler solution
"Cross-border train travel is still too difficult for many citizens" were the words in Ursula von der Leyen's political guidelines for the 2024-2029 European Commission (PDF here). The document continues, bold is my emphasis: "People should be able to use open booking systems to purchase trans-European journeys with several providers,