My best guess is they hope to make up lost with items Amazon doesn't even list. I know there's some products that are owned by BestBuy, I forgot the company name for it, but some random electronics they sell.
Right, Amazon does not list Best Buy's house brand 25 dollar USB-A cable.
Some of that convenience stuff is so ridiculously over-priced(even compared to Walmart) and so restricted in choice(only option is the Best Buy brand) it must be integral to their business strategy.