Big families are more common in the US. While average fertility isn't that much higher in the US compared to europe, the US has a lot of subcultures where it's much higher. Maybe that's part of Costco's success. These tubs aren't oversized if you have four kids.
Living in Okinawa I also noticed the proliferation of reseller stores. They charge a reasonable margin and let you buy 4 or 8 muffins instead of 50. It makes perfect sense in Japan.
Incidentally I was disappointed that 90% of Costco Japan's goods are Japanese origin. You'd expect them to be full of American stuff but the majority is not. Even the imports are often the same items you can find in other supermarket import sections.
Amazon saves SO much time. Costco is SO slow, a preposterously slow experience. Minutes of ordering and unpacking Amazon Fresh takes hours for Costco. And the food is fresher.
It is dark patterns in retail embodied.
I hate their social media advertising. That is, they pay to tip the scales on algorithmic recommenders, they don't pay influencers or ads.
They really are the thing that Pixar mocks them to be.
Everyone has to stop going there and just buy this shit online.