Staff rejecting tickets because the journey has commenced

[jumble]

Knew this would happen. The m-ticket system is wide open to fraud, and it’s always the innocent who get caught up in the crossfire when revenue protection staff try to catch the dodgers.

There's one fairly big difference - airlines do not sell walk-up tickets. By the time you get anything with a barcode on it, you've specified a flight. It's also specific to your name.

Even flexible airline tickets are just an equivalent of an Advance but where the admin fee and fare difference is waived and refund is permitted.

FWIW I actually think the railway would do better putting names on tickets. That way stations and traincrew could offer reprints if ID is shown, such as if your battery runs out or your phone has been nicked but your wallet with ID not. Almost every train ticket is purchased knowing full well who it's for (I'd expect well over 90% of adult tickets are purchased *by* the person it's for). For the odd cases where it isn't you could have the option for a non-named ticket at the same price but waiving the right to a reprint.

The other issue is print at home PDFs on a reserved trains
I always wondered what happens next if 2 people who are at opposite ends of the train show the guard the same printed ticket with both insisting it is theirs?
in the early days of this I gave a pdf ticket to a guard who simply punched it with his clippers
I was tempted to give him the duplicate one I had in my pocket and ask him to do that one as well but thought the better of winding him up