I am a reluctant Costco shopper. My wife is one of the many customers who really love the chain. Me… not so much. Seriously — someone should wake up Costco’s top officials to the need to focus on their customers. After all, it’s the customers who make Costco successful. When my family owned lots of retail stores, I learned many important lessons that Costco needs to learn. Last week, I had to wait through a long Costco checkout line just to find out it takes only one credit card, Visa, which I wasn’t carrying at the time.