Walmart (NYSE:WMT) offers same-day grocery delivery in many of its stores. Right now, that's very labor intensive: Human pickers assemble your order, handing it off to a driver, who brings your delivery to your home.

That's an expensive process that has to ultimately be automated. Technology already exists for much of the order-picking process, so it's inevitable that will be adopted, since there's limited risk in automating behind-the-scenes processes.

Automating delivery, however, is more controversial. Driverless vehicles represent a potential danger to the public, and while their adoption may be inevitable, we're still in the very early days of testing the technology.