[twitch-chat]

That's how the industry has always worked. Walmart, Costco, supermarkets, clothing stores, pharmacies, etc, all have their own brand of products that they sell on their own stores along with other brands that use their competitor's infrastructure to sell their products. Usually the store's brand is also cheaper.

Why is it an issue with Amazon?

[ProAm]

All those stores do not mandate the prices you can sell your product for outside of their premises.

[twitch-chat]

If true then we should start with legislation to disallow platforms from mandating competitor's pricing if they also sell products in their own platform.

It seems like a good starting solution without having to go for the nuclear option.