While not so much a part of this thread but this situation was along these same lines:
My wife and I went to a couple's house because they were having a block party. We arrived late so got the tail end of folks sitting under easy-ups and having a beer and talking. Our friend's husband introduced us and said "Irma (my wife) is a great singer. You ought hear her sing. Her voice is like Linda Ronstadt's." So a couple of the neighbors said "Really? Let's hear you sing something". Of course there was no music, no musicians, no DJ, or anything else for accompaniment.
I turned to her and told her in Spanish so most of them wouldn't understand: "You're not a novelty act for their entertainment. These people have absolutely no knowledge or appreciation for music or your talent. AND nobody is giving you money to be a performing monkey for their amusement." She got the point and told them that she cannot sing unless there is a band backing her up.
Unfortunately, playing for free puts us into that category of being a performing monkey for people's amusement.