He takes 30% for his platform, what's the issue with Apple taking 30% for their own platform? Quit the platform if you want. If consumers value Spotify enough they will leave Apple for it (spoiler: They won't)
Apple can ask 30% all they want IMO, as long as they allow side loading. Don't use their app distribution platform? Don't pay their fee. That is how it should work, which is how it does work on android (and yes most companies still use the play store, because it is hard to convince consumers to use another store, but at least the option is there. Also you can not auto update apps installed from outside the play store…
2. What does that have to do with Spotify not wanting to pay IAP fees?
3. Should Spotify also allow you to "sideload" the mp3s you bought from bandcamp into their player?