But you could also get creative and do things like have a wall plate with three fixed resistors and a switch labeled as "loud", "medium" and "soft" that gave three pre-defined levels for those that wanted super simplistic operation. Try doing that for a few bucks with a new dgital console or mixer.
It would be pretty easy on a CL series console. You can have up to 5 GPI inputs, which can each recall a scene where a master volume control could be set to any level. The focus of the scene would be just that one control, and the scene would be locked, and a high number to keep it out of the way. The system could be defeated by reloading a show without that control however. I don't use any of the security features, so I don't know if it is possible to lock that kind of thing against a reload. There was a console that had variable level on GPI inputs that would work as a remote volume control, but I don't remember what it was.
Mac