For years, Walmart’s relationship with e-commerce reminded me of a very large man trying to squeeze himself into a very small sports car. I respected the effort. I admired the determination. I also wondered whether someone was eventually going to remove a door. Walmart understood that online shopping mattered. The company invested billions of dollars, bought technology businesses, built fulfillment capabilities, redesigned its website, expanded pickup, launched delivery services, introduced Walmart+, added third-party sellers, and generally did everything short of sending an executive to my house to place the order personally. Still, the basic problem remained: Amazon had spent decades teaching consumers to begin almost every product search inside Amazon’s ecosystem. Walmart had stores, trucks, groceries, enormous purchasing power, and enough physical real estate to qualify as a minor geographical feature. Amazon had the digital habit. Habits are difficult to break. Then something chan...