It wasn't that long ago that cash was king in pubs in the South too - they'd mostly accept card (or at least any pub that did food would due to the larger sums involved), but there would be a sigh as they had to go and get the card machine. It's contactless that changed everything, because it's so much quicker than cash and doesn't require the bar staff to return to the customer to give change, and it also can't be pocketed by misbehaving staff. Indeed, most don't wait for authorisation before saying OK these days, and just shout them back to try again if for any reason it declined. (I actually saw this happen at a corner shop in MK about an hour ago!)
Avanti West Coast have as a franchise commitment a requirement to allow all tickets they sell to be amendable and refundable (if applicable) by all of their sales channels. If everyone was on the same standard e-ticket format (whether it happens to be printed on orange card, A4, a smartphone screen or tattooed onto a horse's backside, well maybe not the horse[1]) it seems entirely feasible that could be extended to "all railway sales channels" as they'd all be dealing in the same thing, and accounting could be automated compared with traditional paper tickets.
[1]
Man attempting to board Class 158 with a horse