For years, European supermarkets have tried to crack the code of the American grocery industry. The lure--a juicy $600 billion market--is exceeded only by its peril--no other market is as cutthroat or has devoured so many players so relentlessly. Some, like J Sainsbury, bailed out after years of fruitless effort; others, like the French hypermarket chain Carrefour, lasted a nanosecond. Ahold, a Dutch company that owns the chain Stop & Shop, was bruised by an accounting scandal. Delhaize, the Belgian owner of Food Lion, holds on grimly as Wal-Mart makes chopped meat of the industry's profit margins.
So why would Tesco,...