Walmart stresses that the robots are there to supplement humans, not replace them -- to eliminate drudgery and the expenses that go with it. This helps workers get to the task of filling empty shelves, and that's a job that the company doesn't see ending any time soon given the difficulty robots still have when grabbing objects. "Store associates will always be better at that," Walmart's Martin Hitch told the Arkansas Democrat-Gazette. And the chief of Bossa Nova rival Simbe Robotics, Brad Bogolea, added that shelf checks can cost a major retailer hundreds of millions of dollars per year. However expensive the robots may be, they could pay for themselves very quickly.

Whether or not the robots see wider use will, unsurprisingly, hinge on the success of this wider trial. Early results are positive, however. And given that Walmart has already made a point of using technology to automate processes like grocery pickups, it's hard to imagine the company turning robots down. The main question is whether or not robots will remain complementary. After all, Walmart is fond of cutting costs whenever possible, and doesn't exactly put its staff on pedestals. While jobs are safe from automation for the foreseeable future, it's easy to imagine robots eventually taking over those positions that don't require human-to-human interaction.