But "Play AC/DC" plays them in Apple Music, not your preferred (or currently used) music player app.
There is no way to set that I prefer Spotify, and I've seen a few occasions when CarPlay showed Apple Music when I started a car (might be related to not having Spotify app in the background, but I never digged deeper).
That's because of iOS was never good at inter app communication (Android's version of intents) and that made Siri a worse experience for users and ultimately doomed it in the assistant wars.
I don't think Apple management sat down and thought, right, how do we kneecap competing music streaming providers? Okay lets build Apple Music support for Siri but not Spotify.
It was just that no iOS apps had deep Siri integration and they've been one-offing implementations for common usecases like timers, alarms etc. for the longest time. I assume someone got a project funded by the Music org to go one off the Apple Music usecase as well and here we are.
Someone just posted that Spotify does work with Siri on the iPhone and Siri on the watch uses the same system so that kind of throws the argument that Siri doesn’t support it out the Window.
Apple also has been adding third party intents for years.
With Shortcuts users can add their own Siri actions and third party apps can exposes programming actions.
Yes - the historical context was my point. Things are fine now, Spotify gets the same capabilities as Apple music, so there's no issue.
The thing they (Spotify) are complaining about now with the EU antitrust case is the 30% gate keeping toll Apple charges which is an entirely different thing.
That's very new. Until recently all you got was an excuse that it doesn't work and a suggestion to use Apple Music instead. It doesn't work on my HomePod yet.