You can change the default music app for siri since ios 14

https://www.macrumors.com/how-to/set-preferred-music-streami...

In the car today I asked Siri to play me a particular song (I have had Spotify defaulted for a while), it helpfully signed me up for a 7 day preview of Apple Music Voice and started playing it there! Where's the FTC? Is Apple too big to fail?

“Play X song on Spotify” also works.

And yet I still can't change the default music app that opens on macOS when I hit the media keys!

You can easily map your own macros....

Or use Linux, the highly advanced MPRIS protocol is capable of tracking multiple media applications and presenting their playback controls. It's like space-age tech!

macOS does the same... The only difference is when you don't have a player open at all.

In recent versions, the "default" is just whatever last played media—if you were watching a YouTube video yesterday, and the tab is still open, pressing the play/pause key will start it playing again. There's even a little menu bar widget (it's called the Now Playing menu, and you can find it under Control Center in the system settings) that shows all the instances of actively- or recently-playing media the system knows about. Whatever is on top (IIRC) is what will automatically be controlled by the media keys.

iTunes Store predates Spotify by 3 years and the idea of a subscription model was hardly unique to them.

Also Spotify has access to all of the APIs it needs. It just refuses to use them.

Correction: I meant integration between Shazam (which can be invoked by Siri) and the Apple Music app.