The stories of Trader Joe’s, Chick-fil-A, Zingerman’s and Union Square Cafe/Shake Shack intrigued me tremendously. All these chains/restaurants are all highly successful. How successful? In 2012, Trader Joe’s sold just over $2,000 of groceries per square foot. Whole Foods? About $1,200. Walmart? $600. Chick-fil-A: The company generates more revenue per restaurant than any other fast-food…