2 points
The codec used for transmission is a tiny part of the production pipeline. Perhaps it is publishers choosing to mostly push lesser quality to YouTube, or videos uploaded before they started using better codecs, or any number of reasons.
The truth still stands that YouTubeโs videos (at keast almost) universally have shitty audio quality.
Besides, look at it this way: YouTube can be accessed for free. Why would the publishers want to push a perfect replacement for buying the music on a free platform? Theyโd make less money.