Cash is dying as its supporters do, bluntly. Most cash zealots are older people.
It's unsurprising that it's doing so first in London, which has a generally younger and more tech savvy population than the rest of the UK because as people get older they tend to move out of it.
During my working life I have generally found that those who prefer to use cash tend to be small businesses for some strange reason!
I hate using cash and for many years, since the mid 80s in fact, I have used a credit card - via Apple Pay in more recent years - to pay for everything I possibly can, settled in full each month by Direct Debit. So when it comes to progress, if the benefits are there, I'll certainly take advantage of them. Some people of course don't want to do that, or indeed might not have that option, for quite legitimate reasons. Just because I do something one way doesn't mean that I should expect everyone else to adopt my own preferences.
As far as rail tickets are concerned, whilst I can certainly see the benefits of eTickets, on balance I still prefer to travel with a paper ticket. My first experiences with smartphones (both iPhones) were not great owing to battery and update problems. Whilst I now have a more recent model which has been problem-free, the issues I experienced before still linger in the back of my mind - once bitten, twice shy and all that. The original APTIS credit card sized tickets were perfect and fitted into your wallet nicely. Since their introduction I have never lost or damaged one. But on more than one occasion, had I been using an eTicket, my smartphone would not have been able to produce it when requested, with all the consequences that might well have led to.
I presume that the main reason for the introduction of eTickets is cost - and transfering that cost from the railway to the passenger - but I'm sure that there are others, such as data information management, too. Some passengers might like that, which is great, carry one using them.
But the most succesful businesses will want to make as many of their products or services as easy to buy for as many people as possible. If the railway wants to encourage passengers to use eTickets that's fine, but it shouldn't alienate those who don't. Costs are not just a P&L line between Gross and Net Profit, some need to be seen as an investment, or an ability to maintain and/or increase turnover. It's all well and good when some say that most people now purchase eTickets, but what they and the railway will never be able to quantify is just how much business they either lose, or never gain in the first instance, and the reasons for that. The ticketing system was supposedly made simpler a few years ago, but it has just become worse, as even a casual perusal of the BR Fares website will testify. During my career I have worked with quite a few IT folk. Many of them are very bright indeed and their skills and knowledge often amazes me. But most of them, not unreasonably, have little if any front-line business experience and I would spend some part of my time acting as an interface between what they wanted to do, and what the customer wanted - and sometimes they were two different things altogether.
Anyway, just my thoughts - I can see both sides of the argument.