Groceries, and all of the other sundry items for sale in modern grocery stores, are, on their best days, a racket subject to price manipulation by the government, growers, manufacturers, transportation systems, and retailers. A major trend in recent years has been the expansion of a few mega-grocery chains, and the subsequent elimination of many smaller "mom and pop" stores from the marketplace. Convenience stores have helped to fill the niche left by by disappearance of small grocery stores, but, by-and-large, they have neither the quantity nor selection that today's shoppers seem to require.
(I went to a convenience store this weekend in search of laundry detergent. It carried one brand in one size - not something that I normally use, and the price was exorbitant.)
Most of the major grocery stores in the Valley of Hell have what is called a "club card" where they offer discounts on selected items in return for their customers' personal identifying information (name, telephone number, address, and email). These cards are scanned during checkout and savings are deducted from the final bill electronically - as if by magic.
It's all a scam, of course. Prices are raised on the selected items so they can be "discounted" at checkout. The poor fool without a club card (like me yesterday) winds up paying an excessive price for not allowing the store to know his information and track his buying habits.
It's bad enough that we have to be held captive to the whims and vagaries - and fees - of big banks who can track our every move and purchase at the click of a mouse, but now grocery stores want in on the surveillance act too!
Orwell's grim future has arrived, and Big Brother prevails!