It would be discriminating against Amazon if they sold it somewhere else for less revenue. As in, retail price minus store fees is a lower amount.
When the price advantage is the size of the fee difference or smaller, that's fair and good for competition and I support legal restrictions on contract clauses that want to block it.
Why do they want to sell on Amazon if they don't think the terms are fair?Amazon isn't a public service and businesses aren't people with inherent rights.
Demanding price parity is completely standard for all resellers and market places, pretty much on all scales and all around the world.
Of course you want more legal restrictions and regulations. That's the standard hacker response to anything that comes up, probably including if you want suger in your coffee or not.
But try to think about why Amazon would put such a thing in their contract. If they were just out to abuse any power dynamic, they would of course tell sellers that they have to put a more expensive price anywhere else. Price parity is fair for all parties involved. And if sellers think Amazon's fees are too high then they shouldn't use Amazon - which is what the great majority of product sellers have decided to.