> App Store can't be the only way to install apps.

Yes, hence alternative app stores. But that isn't the same thing as saying Apple can't take a cut from other App Stores, and surprise, they are.

> But that isn't the same thing as saying Apple can't take a cut from other App Stores, and surprise, they are.

Yes, it is. For Apple to be able to take a cut from other app stores, they need to have full control over said stores, so effectively it's just their App Store under a different name. Hopefully this won't fly under DMA.

For Apple to be able to take a cut from other app stores, they need to have full control over said stores

No, they just need a legally binding agreement.