So yes, it’s arbitrary, but it’s supposed to be. It’s about your gut feeling as a human because that’s the whole reason they’re showing you any of these images.
If it “looks a lot like” a storefront then you’ve really got the same problem as everyone else in the comments: they’re small, blurry, images and it’s hard to tell what it is. That’s also the whole point: their algorithms can’t tell, so they want a general consensus from users. There are images they know and use as a control, but some percentage of the ones you see they’re legitimately not sure about.