But not any more!
We travelled from Basdorf to the Sächsische Schweiz and back lwith a virtual ticket stored on my Beloved's tablet computer; the ticket controllers just scanned the bar-code off of the screen, and after checking the credit card details matched up, that was that. This included local Dresden regional trains as well (though here they didn't have the facility to scan, they just inspected the screen).
Well done Deutsche Bahn! (and it is not often I get to say that). Also well done that all the trains were on time for a change!