Since the user is complaining about the way Mac OS handles the audio buttons, I'm surprised that he doesn't mention the problems with HDMI. I don't understand why the OS disables the audio controls of HDMI outputs. If I press the volume down button, I want the volume to go down. Instead, I get a "I can't let you do that" warning! This is particularly bad if I have my headphones connected to the display (I have both m…
macOS disables the audio control of HDMI outputs because that is what the HDMI specification expects/defines. If you think of all the devices that output via HDMI, Windows PCs are the outlier (afaik, not sure how Linux handles it) in allowing separate volume controls beyond those on the output device. Satellite set top boxes, media streaming devices (e.g. Apple TV - I realise NVidia Shield and some Chromecast apps do…
I genuinely think that statement might be false in more cases than it's true. Certainly in devices I've used personally, the majority have allowed you to control the output volume directly.