[lotsofpulp]

There's a few segments of the customer market that will pay varying premiums for more customer service/quality, but only so much. Costco exists only in areas with above median wage shoppers, and can afford to exist by offering a limited selection of items sold in bulk. Similarly, a handful of retailers can afford to exist in this market, such as Trader Joes/Nordstrom/Apple/REI/etc, but most consumers are fairly price conscious and won't hesitate to shop elsewhere that offers lower prices. Or they can't afford the premiums for these places in the first place.