Walmart sells groceries doofus.
Not all Walmarts - this is a relatively new feature (see the abandonment of the Lincoln store that was too small for the grocery).
And their pricing and positioning strategy is designed to draw eyeballs to high margin "food" of low nutritional value - the coca cola, chips, snacks, high sugar cereals get the better floor space, the produce is shunted to the back. If you look at the sales mix of Whole Foods or even Safeway(Albertsons/Jewel/etc) vs a Walmart, the percentage of total food purchases from Walmart from fresh produce, meats, etc... vs packaged and processed is much higher at Walmart. There is no deli - you can't get an in house prepared pasta salad for example, but you could get a Lunchables!
Another interesting thing about Walmart but also seen in many large chains in the midwest - in the dairy section, there is milk, eggs, butter. In the produce section there is produce. But off to the side is "the organic section" which includes organic milk, eggs, butter, and produce. In the Northeast and West, there is a dairy section where the conventional milk sits next to the organic milk, ditto butter, etc. Produce sections are a bit trickier because there isn't a big "label" on an apple, so the produce section will have organic in one area, conventional in another area, but it's still all in the produce section, at a Kroger in Dwight the organic produce was in a completely different part of the store from the other produce. Often Walmart will eschew the organics completely because their customer base just won't buy it.
We had noticed this in person, but it was real interesting when my wife did a research gig for Earthbound Farms. When they identified shoppers in the midwest who would be willing to purchase organic products, they often did not because they didn't want to be seen in the "special section" of the store with the organic items, but would purchase those items if they were co-located with the conventional items. Summary to Earthbound was if they wanted to increase sales, they needed to lobby the merchants to ditch the "organic section" and just put the organic milk next to the conventional milk.