Fr'instance....I like a particular name brand of black beans. They taste better, and are lower in sodium than other brands. I've found the store brands, in some cases, to be inedible. So....I spend 30c (or so) more, and I get something that I know will be good, and not just thrown away.
Ditto for other foods, and consumables like toiletries, Paper Towels, and so on. I know what works. Certainly willing to try other things, occasionally and in small quantities, but don't want to replace them all entirely.
If the store doesn't consistently stock items, I'm not going to risk a week's grocery budget on a dice roll. Nothing snobby about it.....
And, I've found that WM is good for prepared food (cereal, chips, soda, etc etc etc. Stuff that I shouldn't eat). Wouldn't buy meat and produce there if they paid me, though. Good prices, but it's mostly all Mexican or from Central America. Contrast that with my usual grocery store, where things - except in the deep off-season like right now - are generally grown in the USA. :-)
I’m betting the black beans you like are Bush—they’re my favorite. But now you can buy them in quantity at Sam’s for a nice discount. I don’t like Bush pintos—once again, it’s Lucks.