There’s two separate issues here - on-line booking and e-tickets. As far as online booking is concerned, I fully support and embrace it, and acknowledge it has been an excellent innovation. No need to go to a ticket office in most cases, just use the reference and collected a CCST from a TVM a few minutes prior to departure.
But the concept of e-tickets themselves being convenient / easier is beyond me. Some folks compare / use the analogy of airlines, and airline e-tickets are great - no need for any paper, just a reference number and a name needed, and often not even a reference number if travelling internationally as the name on the passport is usually sufficient for the check-in desk staff to locate the PNR.
Rail e-tickets on the other hand... What’s easier than having a CCST in a shirt pocket and getting it out for ticket inspections and barriers. The phone on the other hand… Especially at barriers, its probably in sleep mode as you approach, need to wake it up, start the reverent app (TOC, email, browser, whatever), find the relevant barcode (may need scrolling if its in an email), and do all this one handed while approaching the barrier while carrying another bag. If you don’t do it soon enough, you clog up the barrier. If you do it too soon and there’s a queue, there’s a possibility the screen will have gone to sleep again before you make the barrier. And again, trying to do this with one hand, carrying a valuable piece of technology that could break if you drop it, while walking and trying to keep an eye on / pace with the movement of other people ahead of you. Then at the barrier - oh, maybe the brightness isn’t up enough, faffing to align the screen with the reader. CCST on the other hand, flip it out of your pocket just as you reach the barrier, insert it into the slot, job done. You seen it regularly - people messing about at barriers because phones aren’t ready. Similarly on the train, I can just put the CCST on the table and carry on watching / listening, no need waste the guard’s time to fire up another app / pause the entertainment / change the brightness, even if I happen to spot the guard coming along. I did this on each of four trains this weekend - CCST on table, guard saw it, checked it and moved on with minimal fuss / delay while others were messing around with phones. Added to which I can put a CCST with my bank / credit card which I always guard with great zealousness, while a phone sometimes goes in a laptop bag in crowds as its too heavy for a shirt pocket and I don’t want to risk it being pick-pocketed - again CCST can be in shirt pocket all the time.
Really, no one will ever convince me that the user experience of a rail e-ticket is anywhere near as simple as using a CCST.