I gather the frame of reference of this thread is Europe? All I can add is to speak from my own experiences here in the northwest corner of the U.S.

I've recently sung several concerts where there were many experienced singers in the audience. I was thrilled to see them from the stage. I was even more pleased to observe as they became a very, very good audience. They were watching, and listening very carefully. I could see as they took in the little nuances that only experienced stage performers notice. After these concerts, to a person they all made comments about the little things they'd picked up on.

Give me an audience of performers any day .... CHEERS, bob(deckman)nelson