It works fine if scanned by a machine though (ticket gate, self checkout etc.)

I've used a third party app for this for a UK weekly pass train ticket you could only buy physically, but if you buy it on a train rather than at a station they can't print you a ticket with a magnetic strip and they have to give you one with a barcode (technically an Aztec code), which you can then scan onto your phone and use at the gate. But I kept the original ticket with me too and would use that if a person asked to inspect it