[sokoloff]

That's because Walmart doesn't offer third-party fulfillment (to my knowledge). They allow select third-parties onto the selling part of the platform (but again, not open like Amazon), but fulfillment remains the 3rd party's problem to handle, which is why the shipping price is still an issue there.

Amazon is providing far more of the value chain than other e-commerce sites, and it's no surprise to me that they're charging for that. If that doesn't work for a given seller, they shouldn't use Amazon. If enough people don't use Amazon, Amazon will have to adjust. I see no evidence that the latter is occurring in great numbers.