Yes, subscriptions to content that can be access through an iOS app aren't required to go through Apple (so long as they are purchased outside of the app), in which case Apple won't take a cut.
Note that this is purely down to Apple allowing it — there's nothing stopping Apple from disallowing apps that do this, but to do so wouldn't be in Apple's interests.
Also, the TV licence is officially a tax. Not that that really changes anything. Apple could still chuck BBC iPlayer off the App Store if they really wanted to, but they'd be crazy to do so.
Note that this is purely down to Apple allowing it — there's nothing stopping Apple from disallowing apps that do this, but to do so wouldn't be in Apple's interests.
Also, the TV licence is officially a tax. Not that that really changes anything. Apple could still chuck BBC iPlayer off the App Store if they really wanted to, but they'd be crazy to do so.