Patrick, I’m not dissing CostCo (too much). Lots of people seem to like them for their health insurance practices and so on.
Good point about the availability of books—although (hopefully) kids are surrounded by books in school and have library access. I do love seeing books in non-bookshop shops, though. Museums, cafes, gyms, etc.

50% of the families in this country never set foot in a bookstore. The parents in those families may be lost to book-reading. But the kids aren’t. Having a selection of books available in the kinds of places where those families _do_ go is a really important enabler of social mobility.

With the ongoing radical consolidation of mass-market paperback distribution, so that the grocery store racks that used to offer 144 different titles now offer maybe two or three dozen, book publishing is reverting to its pre-WW2 condition of being primarily aimed at the carriage trade. That carriage trade is now far bigger than it was in 1940. But it still reaches only half the country at best. Those piles of hardcovers and trade paperbacks at Costco are one of the few things ameliorating this.