> but is this similar to Apple though, where they allow you to sign in to subscription services (e.g. Netflix) with your existing account to the service, but don't allow sign ups (which would trigger payment processing)? Or is payment processing baked in there as well?

Actually, looking now, I think you're right. It looks like Spotify disabled setting up subscriptions on PS4. I guess PS4 subscriptions are a small enough chunk of revenue for Spotify it didn't really matter to them.

I guess the real point is that PS4 just isn't a large enough chunk of these kinds of services' market share by revenue to matter; they don't need signups, since not many people primarily use Spotify via PlayStation.