Earlier quoted context omitted.
By "the cost savings have been passed on to the customer", do you mean that a) self-checkout has caused the customer to pay more for groceries, or that b) the cost of groceries has remained the same (or decreased), but now the store makes extra profits from it because they don't have to pay as many clerks? If b) then we're back to where I started: you might as well complain about the discount on Swiss cheese. You don…
Neither a nor b. Take the wholesale price of the product, add rent, delivery, payment processing, in store labour and all the other expenses involved in running a store, then add 1-2%. That gives you the price you pay in store. That formula hasn't changed since self checkout was introduced, but the cost figures have changed.
I still don't see how all this says that "the cost savings have been passed on to the customer", as per your previous comment.