Walmart is about to experiment with autonomous grocery delivery in a big way. The big-box retailer is launching a pilot program in Houston that will use Nuro's self-driving R1 vehicle to shuttle food from "select" stores to customers who've opted into the program. The companies didn't outline how customers would enroll, but Houstonians can expect service to start in the "coming weeks." The test run will help Nuro and Walmart "develop and refine" their services, including providing the best "end-to-end" experience for shoppers. Kroger's earlier use of the vehicles takes scheduled orders through a mobile app, with store staff loading the R1 before it makes its way to a customer's home. It could be a long, long time before you can simply assume that a driverless courier will be available to spare you a trip to Walmart. Nuro's current vehicles are relatively slow, and there are all kinds of real-world challenges (such as snow) to overcome. A lack of consistent regulations for self-driving vehicles will also limit where and how these robotic couriers can operate. This is more of a peek at the future of food delivery than anything else.