Story by Nathaniel Meyersohn, CNN BusinessVideo by Bronte Lord, CNN BusinessPhotographs by Dina Litovsky Profits are razor thin. Online shopping and home delivery are changing the way people buy their food. Dollar stores and drugstores are selling more groceries. Pressures are so intense that regional chains like Southeastern Grocers, the owner of Winn-Dixie and Bi-Lo, filed for bankruptcy. Large companies increasingly control the industry, which had long operated as a dispersed network of smaller, local grocers. And even Walmart — the largest player of all — faces new competition from Amazon, which bought Whole Foods in 2017 for almost $14 billion. But when Walmart’s US CEO Greg Foran invokes words like “fierce,” “good” and “clever” in speaking almost admiringly about one of his competitors, he’s not referring to Amazon. He isn’t pointing to large chains like Kroger or Albertsons, dollar stores like Dollar General or online entrants like FreshDirect and Instacart. Foran is describing Aldi, the no-frills German discount grocery chain that’s growing aggressively in the United States and reshaping the industry along the way. New customers may be jolted at first by the experience ...