My local supermarket is about 200 yards away from my front door and is a medium-sized Sainsbury.
I usually do my shopping at 8am, when it opens.
At that time there's usually one staffed till, but that matches demand reasonably well. I much prefer to use it and there is a flow of generally older people who think likewise. Later in the day it has more staffed tills. In the early mornings much of the traffic is school children and they seem happy to use the automated tills, which is fine by me because I don't end up queueing behind them.
When the booked member of staff is on holiday, the current management seems incompetent, and I sometimes find no staffed tills. It's possible to make a fuss and get someone to step in. However - unlike the previous manager - I've never seen the shop manager step up to operating the till himself. My thinking is that they should, and should give up their back-office paperwork for the time until the issue can be resolved. I've had some conversations with the regular staff and they've said much the same to me. And it happens when staff are booked to be on holiday, not just because of illness.
But, apart from this, it's a good shop and the staff are friendly and helpful, and in any case it's my only sensible choice given its proximity. I chat to them because it's the nice thing to do and helps pass the time. I don't live on my own but I suspect a significant number of the older population do and for them it's perhaps important to have a human interaction, rather than fighting the terrible self-service machines (OK, they are an acquired habit that I haven't acquired).