Linux has HDMI volume control? Interesting. This piqued my curiosity and I wondered if Linux supports ReadyPlay and other DRM standards to support higher bitrate and higher resolution Netflix streaming.
It does not.
You can only get a low bitrate, awfully blocky and distorted (although pretty high resolution 720p) on Linux. The resolution is useless tho because the bitrate is so low.
I pay for my Netflix subscription. And when I want to watch a movie on my projector, I first torrent it (fiber optic, takes two minutes top), then play it. No random Internet issue. I torrent the x264 "webRIP" which I figure out is basically the film I paid for the right to watch using my subscription. I'm not a "data hoarder" / movie collector: I watch the movie then delete it. Same for series.
I started doing this after I upgraded my Netflix subscription to a higher tier then noticed streaming quality on OS X was still crap.
If you’re using Safari, streaming quality will be the same on OS X as on your smart TV. If you use Chrome or another browser, yeah quality does suck.
Chrome does not support the DRM that the studios require for higher bitrate streaming
I may be missing the intended point, but AFAIK neither Windows nor Linux support HDMI volume control (I use all 3 regularly, but only Windows and Linux over HDMI). My Nvidia GPU is connected to a 4K 120Hz TV using HDMI for audio, the TV volume controls are independent of the OS volume settings. Unless OP meant macOS doesn't allow setting the volume independently of the HDMI device.