You're right. I should have said that we keep the volume lower around them. Truth be told, it's not that loud to begin with. About what you'd have in your car. I can't hear it at all 50 yards away.
We ask as a courtesy, because there are those that need or prefer absolute silence in their game, and if they'd rather not play with us at all, they should have that option prior to teeing off.
Shooting par has absolutely nothing to do with the context of "scratch" golf. For exactly the reasons you outline.
editted to add that it sounds as if we agree.
If someone tells me they're scratch, I expect to get my full course handicap from them in a match. FWIW, although other less skilled players may refer to a 2ish hcp as scratch, I've never heard someone who is a 2ish hcp refer to themselves as such.
No music allowed on the course at my club unless it comes from one of the houses along it.
I can tolerate most types of music so it wouldn't bother me but I could see how it causes problems given how diverse music choices are and how passionate some are about not liking certain types of music.