The insurmountable problem is that the practical interests of "consumers shopping on Amazon" don't actually align with the abstract interests of "consumers in general" that the government is purporting to defend. On Amazon we want to find the right item (search, description, reviews), have strong confidence in the inventory and shipping promises (fulfilled by Amazon) and have reasonable confidence we're not getting screwed on price including shipping (Buybox, Prime eligible etc). If you chop those things apart it becomes essentially impossible to offer the overall experience that consumers clearly prefer.
The cause of this is that it should be an anti-trust violation for any wholesaler or manufacturer to dictate retail prices to the retailer. They agree on the wholesale price because that's what they're negotiating with one another, then the retailer chooses the retail price in their store.
Now if Amazon wants the MFN clause, no problem -- but it's the wholesale price they can't sell to someone else below, not the retail price. If Amazon wants the lowest retail price, that's up to them.
