When this robot was added to my hometown's grocery store my family was similarly mystified discussing it, but my father is an insurance professional and said it's a really serious liability expense for grocery stores to manage spills. People who slip and fall on legitimate accidental spills that weren't attended to promptly will sue the grocery, and there are people who will create spills to self inflict injuries for the same reason. His opinion was this kind of oversight is a no brainer for a grocery to reduce the liability overhead, but we also couldn't determine why that's better accomplished with a robot than cameras in the ceiling. Maybe to reduce perceived "big brother" vibes?
Edit: I don't think your comment should be downvoted below the fold, because I think it's pretty natural for people unfamiliar with the operation of a grocery store to have a knee-jerk skeptical reaction to putting a robot in one
I can see how this could, theoretically, help manage spills and related injuries. However, at least the one near me is so slow. It would take hours for it to do a round of the store. It spends most it's time standing still in an attempt to not get in the way of passing shoppers. I'd think that having a stock clerk make a round of the store every 45 or hour would work much better. A brisk walk across the top of the aisles, looking down them for spills, wouldn't take more than a few minutes.
Edit: I don't think your comment should be downvoted below the fold, because I think it's pretty natural for people unfamiliar with the operation of a grocery store to have a knee-jerk skeptical reaction to putting a robot in one