Not all delivery is created equal, however. eBay says the real action in delivery is in site-to-store delivery. Consumers only want same-day service for groceries. That may explain Wal-Mart 's success. It was an early developer of the shop online, deliver to store for free model. So prominent was its effort other retailers were forced to join for their survival. Now it is expanding the click-and-collect model to groceries. It's Asda grocery store chain in the U.K. has offered drive-thru services for years. It will be applying those lessons learned to the states. Now the post office wants to deliver your groceries too.