Spotify is obviously going to try and define the relevant market as something that frames Apple as dominant, but I'm struggling to figure out how they're going to do that. You have to define the market as some set of products that are "interchangeable" to consumers. Apple is under 20% of "smartphones," globally, and somewhere around 25% of the EU.

I don't think you can say that the App Store is itself a relevant market. Especially when you consider that Spotify's exact same services are offered across many other platforms. When you can interchange Android Spotify and iOS Spotify and receive the exact same product and services from Spotify, then how can you frame Apple as a dominant undertaking?

If multiple companies are selling the same product, and one company is making more profit from this product than all the other companies combined, wouldn't you say that this company is dominant?

It's not about what I would say, it's about how a dominant undertaking is defined under EU law. Which isn't just "ah that makes sense" as it's basis. There are legal statutes and court precedent that must be argued to prove the definition of the relevant market, and then to prove that Apple is a dominant undertaking within said market. None of this has to do with my feelings about Apple or how "fair" they are being. I have zero knowledge of EU case law, so it's hard for me to make a definitive, sourced argument here to answer your question. I just don't think it's such an open and shut case of market definition NOR Apple's dominance.

No. I would say that that company is more profitable.

Is Porsche more dominant than Toyota?

It's not about how much dominance it has. It treats its own music platform differently (not subject to Apple Store fees) than any other music platform.

Like Microsoft bundling/treating IE differently to any other browser on its platform.

Lots of regulations in that area are tied to market influence. The Microsoft case was about Microsoft pushing IE through their dominance in PC sales.

It feels like 99% of people are skipping over this necessary condition of Apple being a "dominant undertaking," as defined by EU law, which seems very tenuous at best, no matter how you try to frame the relevant market.

It dominates the profits (87%)[1] which probably correlates with the premium subscriber market.

[1] https://www.forbes.com/sites/chuckjones/2018/03/02/apple-con...

That's not how you measure market dominance.

Not sure why you’d use the EU as the market indicator. They dominate North America, which is where the biggest market is. In the EU, they are the second largest behind Samsung but it’s close and they change spots from time to time.

Because Spotify has filed a complaint with the EU about Apple's behavior, which is why we're talking about all this right now.