Amazon’s recent reveal of free one-day shipping for all Prime members almost blew up the internet.

The real question is why is it a big deal? Amazon’s (AMZN) rival Walmart (WMT) is already shipping groceries same-day at 800 stores mostly through the use of independent contractors such as DoorDash and Roadie. By year end, Walmart expects to have this capability available to shoppers at 1,600 of its U.S. locations.

Walmart also just took the wraps off its own one-day delivery program this week.

So in other words, been there, done that Amazon. What’s next on the delivery front you ask? Walmart and autonomous vehicle delivery mixed with some drone action, says Walmart’s top executive.

“I think last mile [delivery] is going to be solved in a lot of different ways,” Walmart CEO Doug McMillon told Yahoo Finance in an interview at the company’s Arkansas-based headquarters. “We're developing the capabilities to be able to solve last mile in lots of different ways — I think autonomous, as it starts to happen, will be another interesting part of the puzzle.”

McMillon said Walmart will soon begin testing autonomous delivery in Arkansas.

Walmart’s venture into autonomous delivery arguably continues to garner little fanfare (beyond a home-run TV commercial this year featuring the autonomous Knight Rider car, KITT, venturing off to pick up groceries), but it should considering the speed in which tech savvy consumers are demanding their orders nowadays. In February, the company teamed up with logistics giant FedEx to test delivery via an autonomous robot. The robot looks like a giant cooler on four wheels.

The test with FedEx comes almost a year after Walmart inked a deal with Google’s Waymo self-driving unit in Arizona. Waymo’s self-driving cars essentially show up to take customers to the stores to pick up their orders and then back home.

“Recognizing that a significant portion of Waymo rides taken revolve around running errands, we partnered with Walmart to make shopping more convenient and to give riders savings on groceries that were ordered on Walmart.com," Amee Chande, chief commercial officer of Waymo, told Yahoo Finance. "We are proud to partner with businesses like Walmart to explore ways to further connect the community to businesses and to learn key consumer preferences like where people prefer to be dropped off and picked up when they go shopping."

Need for speedy deliveries

In the end, the world’s largest retailer — and others in retail more broadly — must find ways to deliver packages even more quickly with an eye towards profitability on those orders.