“Court” music is about being a display of power that doesn’t threaten your neighbor into thinking they need to start building an army. That’s why the music itself epitomizes precision and control. Classic soft power.
It’s conspicuous consumption. You keep musicians on staff to demonstrate that you are so rich and powerful that you can afford to blow it on something so frivolous that it doesn’t even feed anybody, it doesn’t stick around, and you’re either there to hear it or you’re not. See Haydn for the very best example of this model.
Sheet music then becomes the “advertising” so that people can be aware that it’s happening.
However, I think sheet music eventually became (and later, records/CDs) mostly a pure exchange of money for music.
I guess what I’m trying to say is something in between: the exchange itself can be pure on both sides (creation/consumption), but music is “of” society/culture and almost always serves many other purposes in the power structure of societies.
In its very purest form, buskers have almost always been very poor.