10 years, or so, ago, Safeways used to have a hand-scanner than fitted into a cradle on the shopping-trolley. You picked the item from the shelf, scanned it and packed it into your bag/box.
At the end, you placed the scanner back into its unit where is issued an itemised receipt which you simply took to the till and paid the amount asked. Occasionally it would ask you to put your shopping through the checkout as usual, I suppose the thought that there could be a random check kept most people 'honest'.
I was so much easier and I've never understood quite why more supermarkets didn't take it up.