Amazon drones make 100th delivery, lagging far behind Alphabet's Wing and Walmart partner Zipline

Amazon says its Prime Air drones recently completed 100 deliveries in two small U.S. markets. Meanwhile, competitors like Alphabet's Wing and Walmart partner Zipline have made hundreds of thousands of deliveries, although most of those have been overseas in Australia and Africa. The U.S. is a tough regulatory environment, with strict rules about flying over roads and people and beyond line of sight. Yet some companies have been granted broader certifications. Here's how Amazon fell behind.