And no offense :), but I don't go to the grocery store to make friends. I have much better or more interesting things to do. If I could get fast reliable delivery and not even have to go, I would choose that option.
The point relevant to the OP is that self-checkout systems can be implemented well.
My grocery store, however, is 20 minutes away in a neighboring town. They have a large staff which is in frequent rotation. The staff also is mostly early 20s or younger age. Add all these things up, and it just doesn't make much sense for me (or them) to go out of our way to socialize.
You fundamentally need to trust that your customers won’t try to steal from you, and that if they do they will be moderate enough that you can track it as a cost of business - or so extreme that your staff will catch it easily (and care enough to fix it).
Many people, unfortunately, do not live in such places.
If they could make this system work with anonymous accounts (walk up, swipe credit card and pick up scanner, put back scanner when done and the previously-authorized credit card is charged the appropriate amount) it would be lovely.
Of course, when you checkout with a non-cash payment, they can keep records of what you bought based on your payment info.
In the land I live, I just do this:
1. Enter the store and immediately present my loyalty barcode from my phone app to the scanner
2. Pickup a hand scanner which is now associated with me for this visit (I could even use my phone as a scanner, but I haven't tried it; I assume it wouldn't be as fast as the good laser hand scanner device).
3. Scan every item as I put it into my cart. If I buy multiples, I tap the + button on the scanner after I scan. If I buy produce that needs to be weighed, I go to the scale kiosk, put the thing on the scale, make no more than 3 taps of the screen, and then stick the printed label on my item and scan it.
4. To finish my shopping, I go to the checkout area and drop my scanner into a slot. Then I walk to the checkout kiosk of my choice and scan my loyalty barcode (from my phone app or from a plastic keyfob thing). The screen shows details of what I bought, but I ignore that and quickly pull up Apple pay with my bank card, move the phone near the card reader, and pay my bill.
5. Tap the screen to choose physical short receipt (just a barcode used to pass the exit gate), long receipt with barcode, or opt to use my loyalty barcode to exit.
All of this is so easy, and the experience is refined to the point where there's little left to improve.