They benefit substantially from open source and give very little back in concrete financial terms, yet complain that Spotify is asking the same thing and portray them as freeloaders. In reality, Apple are doing far more freeloading off of other projects than Spotify is doing off of them, legal or no.
What Apple have created in the App Store (a software package repository on an OS platform) is a monopolistic trust over what should be a free marketplace, like how regular GNU/Linux package repositories have worked for decades. This is exactly what "anti-trust" is supposed to prevent and the DoJ need to have the balls to start breaking up tech companies for this shit, just like they almost did to Microsoft.