If you believe the FTC in their current active anti trust case, the reason for this is that if Amazon sees your product for cheaper elsewhere (even if it's the

If you believe the FTC in their current active anti trust case, the reason for this is that if Amazon sees your product for cheaper elsewhere (even if it's the same after shipping), they will down rank your product in search results and add friction to the buying process. Since no manufacturer can risk having no Amazon sales, this means the manufacturer requires a base price that matches Amazon. Amazon recoups free shipping cost through additional merchant markups. This means consumers pay increased prices everywhere, and we are all indirectly paying the free shipping cost even if you walk into a store.