> So companies are making less on the products they sell through Amazon because as you say "sellers want to do is pass that fee on to the customer" but can't because Amazon's policies prevent this and this bad for the consumer because?
It's not clear whether it's bad for consumers who shop using Amazon, since they're getting some hand-wavy amount of "value" out of using Amazon's product search and free shipping. But it's certainly bad for consumers who shop directly from a seller's website. They're essentially subsidizing the seller's lost margin on Amazon sales without realizing it, and not benefiting from the free shipping or rewards points that the Amazon purchasers are.
The net effect is it doesn't make sense for consumers to shop anywhere but Amazon if a seller has already decided to bite the bullet of selling on Amazon. You'd think the free shipping and rewards points and hosting costs and Amazon's profit margins would all contribute to the price being higher on Amazon, but they don't because of this policy. So as a consumer, you're crazy not to take advantage of those rewards (or you're just feeling charitable to the seller, who does make a lot more when you buy directly).
> You also didn't explain why businesses are forced to use Amazon.
I'm not arguing a position anywhere near that outlandish. In fact, I'm not even trying to argue for a position! I'm just trying to describe the effects of Amazon's policy on the market. For what it's worth, I don't think their policy is uniquely onerous. For all I know it's significantly less restrictive than some of the deals brick-and-mortar stores have struck with their suppliers.
We probably agree that the "correct" way to deal with this is for suppliers to quit Amazon and lower their prices, if they truly think they're getting a bad deal. But the unfortunate reality is that our markets are extremely heavily regulated, so you'd be a fool not to at least try the courts now and again to see if you can make your deal better that way.