Netflix does not allow you to sign up in their iOS app. You have to sing up and set up payment through their website, but you can use your username and password to use your subscription in iOS. They do not pay the Apple Tax.

Hey tried to use the exact same, but Apple said they MUST allow sign ups in the app, using in-app purchase API, and paying 30% to Apple. Apple was not going to allow Hey to do what Netflix/Spotify/etc have done for ages, until public sentiments and social media storm forced them to acquiesce.