I don't think you considered the loss of the 30% from each apple music customer's previous subscription to a competitor. There's no unfair advantage, the maximum profit apple can make by switching a customer away from spotify is spotify's profit.
In my view the potentially anti-trust advantages Apple has over Spotify mainly come from the fact Apple Music is preinstalled and is promoted to iOS users through push notifications.
Spotify would be free then and are now to make a web based player like youtube or soundcloud.
Let's be honest here, the 30% spent by Europeans is mostly going to anonymous bank accounts in Jersey.
Alternatively, if for some reason there's just a single lump of music streaming revenue to be earned, maybe it's still shitty if Apple steals spotify's business but breaks even on the opportunity cost.