7 years of Music being the exclusive audio app with Siri support is a particularly crappy example.
I'm sure it takes some work on Apple's side to make that work for 3rd parties, but I'm also sure Apple knew that Spotify users (and many other music apps) wanted it and could have done it sooner.
Apple has been adding more domains to the SiriKit API with every iOS update since the API was added in iOS 10.
>Apps adopt SiriKit by building an extension that communicates with Siri, even when your app isn’t running. The extension registers with specific domains and intents that it can handle. For example, a messaging app can register to support the Messages domain, and the intent to send a message.
Originally it only supported VoIP calling, Messaging, Payments, Photos, Workouts, Ride booking, Car commands, CarPlay (automotive vendors only), and Restaurant reservations.
The next iOS version adds SiriKit support for playing music.
So... Apple added support for domains that don't provide them a competitive advantage well before they added support for the domains that do. Is this supposed to make it look better?
FaceTime and iMessage are features that are used to sell iPhones (and the ecosystem in general), they are not products that exist to directly provide a revenue to Apple.
I am not super familiar with Apple Cash, but my understanding of it is that it also falls more on the Feature side and doesn't exist to provide a revenue stream on its own (hence why there are no fees for debit cards).
iTunes is clearly more of a product as it creates a significant revenue stream for Apple.
It makes sense that Apple cares less about competition with its features as that leads to a better user experience and more iPhone sales while Apple cares more about competition with products as that cuts directly into their income.
I'm sure it takes some work on Apple's side to make that work for 3rd parties, but I'm also sure Apple knew that Spotify users (and many other music apps) wanted it and could have done it sooner.