The real issue is not smartphones, iOS and Android or apps. The issue is that independent technical standards are intentionally ignored. There is no reason that I should not be able to set my plan through curl and hand-draw the QR code with pen and paper. Sure, I would not want to actually do it like that, that's not the point. The point is: if I can use curl and pen & paper, then I can use whatever else I want. If I want to use a smartphone I should be able to code my own app according to a well-documented public API. Those APIs already do exist, otherwise the official app would not work, so it's no extra work for the service provider.

We need a law that mandates open specifications for access to all publicly available services.

You may not like or disagree with it. But it's the true answer.

Even better, in NRW region some ticket models are only available on the app, nowhere to be found on the ticket machines or at the counter on the stations.

Are there no passes? e.g. in Budapest I have a monthly public transport pass and I just board the vehicle when it arrives without having to validate or purchase a ticket every time.