We have Dollar Generals, Dollar Tree, and 99c Only stores. They are all always packed. And yes, you can actually grocery shop at the 99c Only store. They carry fresh produce, milk, bread, and then almost anything else you want. After my dad died my mom did her weekly grocery shopping there. Of course if she wanted a steak or something she had to go to a real grocery store but all her every day stuff was from the 99c Only store.
The Dollar General by me has bread & milk; I’ve never seen produce there - and that specifically was why they were deemed as contributing to “food deserts”.
It does a lot of business, but not with normals; a lot of public assistance types. Normals would tear their hair out waiting on the checkout line.