Go to a Wal-Mart on Friday night. Obese people on motorized scooters in the candy aisle fruitlessly reaching for their one sugary desire that is just out of reach. Or the women in pajamas and bunny slippers (all ages and all sizes). Hispanics with their bambinos clogging up the aisles. Wal-Martians doing their slow methodical zombie walk. The vacant looks of mental deficiency. Darwin missed the boat with these survivors.
Granted I do not go to Wal*Mart that often but only because Meijer is a superior store. Always go for the place that is not on the stock exchange if you have the option. :)
But since they are all in the same general area I would assume the same people shop at both and I have never seen the people you described in any great quantity. Are there some? I guess. Obese people but most of them are walking around. I don't think I have ever seen someone in night clothing in the store, when I worked at the gas station it was another story. Hispanics yes, but not clogging up the aisles and most of the people who are slow walking are either elderly or looking for something that was moved in the last store reset.
Maybe it is in what you look for. I don't know. But it puzzles me.