Counter-positioning is usually a startup's weapon against incumbents. Costco, a $230 billion company, has somehow developed counter-positioning power against Amazon: its model structurally requires customers to come to the store, which is the only reason prices can be as low as they are. Amazon's convenience model and Costco's value model are mutually exclusive — and Walmart's Sam's Club has actually shrunk while Costco grew its US warehouse count by a third.