My impression of Costco's selection is that it's the retail distillation of car-centric suburbs, despite it not being exclusively those people who shop there. The happy suburbanite cares about convenience and quantity above all else, from what I can tell anyway. They don't really have a varied sense of taste, they just want stuff, and they want easy access to that stuff. They like a "haul" that they do once a month, and buy vehicles that will fit it.

For me, I'll join a friend who has a membership from time to time, but I'll only get chicken breasts, a rotisserie, maybe frozen fruit if the price is competitive, and... soap; everything else is just noise and/or extra calories that I wouldn't have bought anywhere else but happens to fit in the industrial-size cart and usually isn't a substantially better price, or it's just not a good offering. I could buy greek Yogurt cups, but really I don't want that brand or the lemon or lime ones, so I'm paying marginally less to enjoy half of them. I could buy salsa, but unless it's a party, I have no need for a year's supply. It's just a lot and it's probably kind of agreeable. Also the blankets, they're alright.

The small selection of things I get are the few items—as the probably AI author suggests—that I'd either buy anyway in smaller quantities or just don't have opinions about. The one time I actually did have a membership, I'd find myself working backwards from it to justify to expense. I let Costco borrow my money and to get it back I'd need to exploit their good deals, but ultimately they just made a killing off of me filling my cart with arbitrary bullshit stuff.