classic aggregation theory to create a monopoly.

the only way to prevent such things from happening is e-commerce is spread across non-platform channels but independent ones e.g woo commerce etc where a seller runs and hosts their own shop, then maybe go to semi-platforms such as shopify etc that don't aggregate everything on one storefront.

because sellers are reliant on amazon bringing in shoppers, unlike say woo commerce & shopify - then yeah amazon feels rightly so that they need to take 50% margins on a seller's item.

the same thing plays out everywhere where some producer is reliant on someone bringing in the buyers - uber, Spotify, apple App Store.