It's not relevant. If the word Costco is too distracting to interact with my point, then replace it with any place you might want to go in a day.
The lack of infrastructure is what makes the routine unpleasant, not failing to carry a small bag of bagels home. Not even the weather since riding a bike casually creates a breeze.
My point was that if you want to bike to get things you need, you have to go to places that are on more local scale.
A place like Costco can only exist with the support of a large amount of car infrastructure. So if you want to go there that's what you have to deal with.