Yes. I don't personally, but know Kmart at least is cheap for clothing basics, especially for kids. It also has cheap homeware and small appliances. Not everyone can afford to buy expensive brands.
Edit: should also point out, they pretty much have clearance stuff on sale weekly, so people probably go to see what they can get for cheap.
I get most of my everyday clothes from Target. You get the occasional dodgy seam, but for jeans, trackies, and t-shirts they're pretty good. In no way haute couture, but it's $10 a t-shirt.
Perhaps people that buy lots of chocolate and confectionery? That's the biggest theoretical demographic I can think of (my only other thought are people that buy new clothes and underwear rather than using a washing machine, but I don't think that would be many).
I suspect your frame of reference for this might be from somewhere other than Australia. Neither one has groceries in Australia, other than a small selection of snacks.
That said, almost every shopping centre where you get one of the big supermarkets, you'll also get at least a Kmart or Target.