I don't think the real issue is with cash versus card, for most shopping payment is made by card nowadays but for buying odd small items or if you are just buying something you know can only be obtained at an artisan store cash is still common. The issue with the railways is that the ticketing system is unduly complex and the TOCs will enjoy PFing or even prosecuting people who've been forced to buy tickets from a machine which offered them a lack of choice or the incorrect choice as first option, and they pushed the wrong button.
I was in Budapest last summer and was wanting to go out to Szentendre on the local rail network, we took the tram to the nearest interchange station, and there was no ticket office! However the machines had an English option, which even pointed out that the add-on ticket you needed to buy from the boundary station if you already had a city pass. I haven't the confidence in the UK ticketing network or the TOCs to offer anything comparable to this experience
I know of people who give their credit card AND PIN to their teenager and send them out to the shop for a few items when they can't be bothered putting their shoes and coat on themselves. I think you'll all know what happened next!
I was in Budapest last summer and was wanting to go out to Szentendre on the local rail network, we took the tram to the nearest interchange station, and there was no ticket office! However the machines had an English option, which even pointed out that the add-on ticket you needed to buy from the boundary station if you already had a city pass. I haven't the confidence in the UK ticketing network or the TOCs to offer anything comparable to this experience
And the massive benefit of this is that if the kid is stranded you can transfer as much as is necessary to get them home safely without just giving them a £20 note and risking it'll be stolen by bullies or spent on sweets, and you can see that that's what they spent it on, too. And if the card is lost or stolen by bullies it can be stopped, unlike cash in a wallet or pocket.
It's inconceivable to me that anyone in 2023 wouldn't want their kid to have one of these, even with a fee (which is quite small, a couple of quid a month I think, on the ones that charge).
From age 16 (mid 1990s) I had an authorised user card on my Dad's credit card, with a strict rule of "you phone and ask me before you use it". That obviously carried an element of trust. But why would you not have something that has the capability of that without the trust risk and at more or less any age where a kid would be out unaccompanied? And obviously if old enough they can have a conventional online-only debit card on their bank account anyway, I think that's from 13?
I know of people who give their credit card AND PIN to their teenager and send them out to the shop for a few items when they can't be bothered putting their shoes and coat on themselves. I think you'll all know what happened next!