What you're failing to recognize is that the coffee shop owners are, for lack of a better term, profiting from the music being played in their establishment. In a more direct case I can speak to, I frequently purchase beer from the places where I've played open mics. They directly profit from hosting the event, and feel that they should be exempt from paying the compositing artist association dues...why?
Now, for street performers, they are providing a service akin to radio, insofar that they are publicising a song, not charging a cover, and further advancing the arts and society's respect for them (putting aside the quality of the performer). That's why my local city has ordinances actively supporting busking - provided no solicitation for compensation is put forward - because it makes life better. In turn, performers are allowed to have a tip jar or accept compensation as they are benefitting society and the arts through the "practice and performance of their craft" as the ordinance describes it.
The Satire/Parody Distinction in Copyright and Trademark Law— Can Satire Ever Be a Fair Use?
Supreme Court also ruled that Satire/Parody is Fair use protected due to their verdict in Campbell v. AcuffRose Music, Inc
https://apps.americanbar.org/litigation/committees/intellect...
So your recommendation to all the street performers? If open mics are "stealing" from the artist then street performers are at a whole new level. We will have no art or performance in our society if we continue these down these roads of copy right and performance.
Only one's that can do anything reflecting to society will be satire and that is only because of the Supreme Court.