I'm really struggling to imagine a world in which this is preferable. Produce is the obvious example but it's much easier to consider what all I'm purchasing and what else I need to get when I can just look in my cart at what I already have.

I mean the checkout experience might be a little better but there are so many additional variables that come into play. Like are things going to be bagged well? I walk to the grocery store so it's important to me to get a good weight distribution between bags.

Idk this just seems like a solution to a problem that doesn't really exist.