"Lingering by the nappies? How about a special offer on formula milk?"
I often linger near the nappies but would never need formula milk because I have no kids. I would be in that isle to buy baby wipes for the gf. She uses them for various non-baby related purposes including makeup removal. This is the same logic that causes Google to show me adverts for hotels in the place where I have booked my summer holiday, but since it's already booked I have no reason to click on those adverts.
How accurate is this wifi tracking? Isles in supermarkets are pretty close together, are they sure I'm in the nappies isle in my local Asda and not the unrelated isle next to it? How about at the end of the isle next to the magazines & newspapers?
As usual this is tech we as consumers have never asked for, have no need for and don't want. It probably won't even do the thing it is supposed to do very well most of the time.