Of course that's an issue - but I don't think it's the main reason.
If you go back in time to when the original super market designs were made, prices where on items with printed labels and the person at the checkout actually did the adding up by entering the numbers!
ie checkouts originally existed because adding up to total cost was a non-trivial job, and then you had to hand over cash and somebody needed to calculate the change, work out how you split that into the notes and coins and count it out.
Overtime these steps were automated way - first with barcodes for cost totalling and then both electronic payment methods and payment machines that take cash and automatically give change.
Then the job just became swiping the items across the barcode scanner and pressing a couple of buttons to enable the electronic payment and it took a while for people to realise the original reason for the job had gone and customers could do it themselves.
If you go back in time to when the original super market designs were made, prices where on items with printed labels and the person at the checkout actually did the adding up by entering the numbers!
ie checkouts originally existed because adding up to total cost was a non-trivial job, and then you had to hand over cash and somebody needed to calculate the change, work out how you split that into the notes and coins and count it out.
Overtime these steps were automated way - first with barcodes for cost totalling and then both electronic payment methods and payment machines that take cash and automatically give change.
Then the job just became swiping the items across the barcode scanner and pressing a couple of buttons to enable the electronic payment and it took a while for people to realise the original reason for the job had gone and customers could do it themselves.