"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."
This is not reflective of the Costco shoppers I know and the place Costco fits in their lives.
Bi-Rite and Erewhon or Citarella and Eataly are not Costco competitors.
To understand the appeal of Costco to suburban families, you have to understand their caloric needs. Costco is the best solution if you need to buy 48 eggs and 4 gallons of milk a week along with 8lbs of chicken, 4lbs of turkey, and pounds of broccoli, green beans, spinach, sweet potatoes, onions accompanied with apples, peaches, mangos, avocados, blueberries, strawberries and oranges.