I'm smiling at those impressed at my resistance - I can assure you it is more apathy than anything more principled or virtuous!
Relying to a few points that have come up:
Parking - we are in a city so drive rarely, mostly to visit family outside the city. We've only had to pay for parking a handful of times in the last few years and so far its been cash or card in a machine. Not caused us pain yet.
Banking - I log in on the desktop or go to the branch. If I need a code it can be texted to my basic phone.
Concerts, theatre, gigs etc - not something we do often, and if I do its usually stuff where you can pay on the door. I print out a ticket if you need a QR code/barcode etc.
Holidays - we havent been on a holiday thats been anything other than visiting family or friends for a while. We are more likely to find ourselves at a cash only camping field than a holiday camp/All inclusive type place so havent yet found our choices curtailed.
Travel and transport - we plan journeys and book tickets on the desktop, pick up tickets at the station, carry maps and timetables and know where to find info on the go. Something I'm teaching the kids to do too, I reckon its a useful skill even if you mainly use a smartphone.
Convenience - I think different things are convenient for different people. Some like to do it on the go, thats great. Convenient for me is being able to store up a few tasks and then do them all at once on the desktop so it doesnt get in the way of the rest of my day, and I feel more organised and on top of arrangements that way. I manage money quite tightly and I this also helps me with controlling outgoings.
I didnt know you could use whatsapp on a desktop - useful to know although I'm probably still going to use the excuse to avoid joining groups.
Secondary is a real unknown area. I didn't use a computer either at school or university so guess I've always assumed all work would be pen and paper based or if they need any technology it would be provided. I'm sure I probably sound ridiculous, there is loads I will need to find out more about here. Slightly separate to smartphones though.
Good points have been made about what happens when DC get older. Until now I've slightly unrealistically thought I'll be able to swerve the smartphone issue with the argument 'I've not got one so why do you need one'. Its clearly more complicated than that though. I guess part of the reason for this thread is to start me thinking about how to deal with that in the coming years.