YouTube uses it for the viewing of full movies that you've bought from Google Play but view on the YouTube website. Which is about 0.0000000001% of the content on YouTube and not terribly relevant to this thread.
The YouTube TV service doesn't use EME, no. And isn't terribly relevant to this thread either.
1. It is relevant because the claim was "YouTube does not use it" not that "most of youtube does not use it"
2. I firmly believe now that EME is standard YouTube will start using it, especially as they start rejecting independent creators in favor of more High Budget Commerical Creators and Tradional media whom they already show a preference for. These Companies will demand it just like the big Movie Studios
3. I am not subscribed to YouTube TV service so I can not confirm but do you have a source or technical document showing they do not. I would be shocked if they were allowed to get Commercial deals to carry main stream cable channels and stream then in the clear with no copy protection.
The YouTube TV service doesn't use EME, no. And isn't terribly relevant to this thread either.