Cause even Google knows their 30% transaction fees are whack.
YouTube has its own CEO. It's part of Google but work as separate company so I guess that's why they're using it separately. Also digital subscription for music and video subscription exempted from Play Store billing. For example, Netflix and Spotify subscription you can buy directly from service provider's website.
Rules for thee...
Correct me if I'm wrong but google is way more lenient on this than apple. You can provide subs outside the play store. You cannot however provide a payment system inside apps distributed within the play store.
First question you should ask is why would you want to?
google does not need to follow its own rules cause they are the company
Google in general seems to behave like lots of very small companies who happen to share the same name.