A couple years ago, I was at a station waiting for a (delayed) ICE train. I couldn't buy a ticket at the machine or with the app, since the train had already departed (if it had been on schedule). The ticket machine also wouldn't take VISA / MasterCard, only the more common Girocard (most people still call it EC)

Later, in the train, when I asked the conductor to buy a ticket with my Girocard, he said "That's not a commonly used payment method" and asked for VISA, or cash (not having any to provide change, obviously).