Soul searching in the UK

UK's Independent asks: The Big Question: Have supermarkets become just too powerful in Britain? From the lede:
Because the Office of Fair Trading (OFT) has said that the UK's four biggest supermarkets, Asda, Tesco, Morrisons and Sainsbury's, colluded with dairies to keep the price of milk and other dairy goods artificially high between 2002 and 2003. The watchdog says that consumers ended up paying £270m over the odds for milk, cheese and butter as a result of the price-fixing deal. It has added fresh impetus to the argument that the UK's supermarkets have become so big that they are able to dictate to suppliers and customers alike, with decisions on how much consumers should pay being decided by a small group of executives.

TK: I'm particularly intrigued by the last sentence "...UK supermarkets have become so big that they are able to dictate to suppliers and customers alike, with decision on how much consumers should pay being decided by a small group of executives." How much does this resemble the U.S., when retail executives determine what the retail price should be and then work that price back to the farm level. Is the sharing of information between buyer and seller leading to greater power for the retailer?