>To have a valid train ticket on your phone (for those without printer), you are also required to accept the google or apple terms of service and privacy policy. You can download a pdf ticket, but the data matrix on there is only valid if you print it out!
How does this even work? QR codes don't magically change when they're printed.
They are just not accepted by the conductor. But those policies can also change in the (IMO) "right" direction, e.g. the German Deutsche Bahn changed their policies a few years ago and now digital tickets are accepted[1] in PDF form on digital devices, while they previously were not.
How does this even work? QR codes don't magically change when they're printed.