You don’t need metaphors or comparisons.

The Spotify app should have a button that takes you to their website, where you can sign up for a premium subscription.

It doesn’t have one because Apple would kick Spotify out of the App Store.

Also - all other links to the Spotify website (support, terms of service, privacy policy, etc) take you to pages where the main navigation of the website has been removed so that you can’t find the signup page. Because again, Apple bans that. For the longest time apps have not allowed to have any way for users to find a signup form on a website.

Apple claims to be compliant now, because they have a new API - only available in Europe - that informs the user that they might be a victim of identity theft, fraud, etc if they continue, then would take you to Spotify’s signup page. Also if Spotify wants users to see that horror show… they’d have to pay tens of millions of dollars per year. Vs not taking advantage of the new API where Spotify doesn’t pay anything to Apple.