App Privacy: Why does the railroad company need my steps made and other health data? How-To revoke?

I was surprised to see that the local railroad company, accesses Health and Fitness data. I use this app only as a timetable for trains.

The Health app can track your daily footsteps and the flights of stairs you climb. You can manually add other information like body weight and caffeine intake, and track additional data with other apps (such as nutrition and fitness apps) and devices that are compatible with Health (such as Apple Watch, AirPods, weight scales, and blood pressure monitors, all sold separately).

Is there a plausible reason why the railroad company wants to collect my health data? How can I prohibit this (expect uninstalling the app and use web site)?

This is required for the EasyRide functionality. The first time you activate it within the app you are asked to grant access by iOS.

^{(EasyRide wants to access your Fitness data to optimally support you, e.g. if you forget to sign-off after a trip)}

If you decline you can't use the EasyRide functionality

You can check in System Preferences -> Health whether the SBB app has access to its data or not. Access can also be revoked from there.