Costco Wholesale's membership rules and policies are constantly evolving, as evidenced by its newest perk for its highest tier of cardholders.Retail is one of the largest industries on the planet, but it's also highly competitive. According to Mordor Intelligence, the global retail market is forecast to expand to $27.3 trillion this year, with an annualized growth rate topping 6% through 2030.Despite the razor-thin margins often associated with retail sales, the rewards can be lucrative for the businesses t ...