Simple explanation: They have the hardware capable of NFC payments at Sainsburys, Ingenico 3000 series. However when they had them installed the firmware didn't contain stable/release NFC reader code, or they didn't opt for that firmware to be installed. There are backend reasons why you wouldn't have that firmware as well.
They have 1374 stores, let's say 15 devices per store, that's 20610 devices not including PFS & customer services. The average firmware update takes say half an hour, field service engineers at £30 per hour. That's £309,150 in time just to enable NFC - let alone travel, subsistence etc. And what is the benefit to Saisnsburys from spending a large chunk on that? Well, very little.
That's how these people think....sod the customer haha
I just used the new version of their self scanning today and what a mess. I opted to use the app, and while you can register on the app and add your Nectar card, you must still show your Nectar card at the checkout (and, yes, you still go to a manned checkout instead of a terminal that you pay at and leave, unless stopped for a random check).
The app is so awful. Needs to use GPS to keep checking you're in store, so in the back of the shop it wanted me to give up shopping as it lost my location (and you can't scan anything at this point). It's the GPS lost, not the Wi-Fi or mobile data connection.
When you are in scan mode, it remains with the screen on all the time and doesn't show what you just scanned or the price. You need to jump out to check the list! What sort of self scanning system doesn't let you see the running total all the time?!
Waitrose has an app and you never need your card again, as it's stored on your account. Sainbury's does too, but they argue that they need the physical card for security. Why? A physical Nectar card is the security risk - lose it and someone can try and spend your money.
On the app, you can PIN/password/fingerprint protect the app! Tesco never needs to see a physical card these days (just use their Clubcard app or a third party one). Sainsbury's has scanners at tills that can't read a Nectar card on a phone screen, as they're the laser type, not cameras.
Can Sainsbury's get anything right? They ditched the old Motorola handsets that other stores still use with no problems, and must have spent a fortune.. and for what? A new app that's rubbish and new scanners that work the same as the old ones, but look nicer.