[alephnerd]

It's also different demographics. Costco shoppers have always been in the highest income brackets, while Amazon's are middle of the pack and Walmart's tend to be at the lower end [0][1].

[0] - https://www.businessinsider.com/amazon-shoppers-richer-than-...

[1] - https://www.businessinsider.com/how-costco-sams-club-shopper...