"It's not the norm, in my experience "
It has been argued for often enough, here and elsewhere, for it to be fairly common practice will.
My particular example was of a nationally recognised singer, making it widespread enough for me to believe it to be a not uncommon practice.
It has been argued for elsewhere as a point of principle that if unless a guest requests that the audience does not join in, then they are free to do so.
"at sessions anyone can join in"
We have a singing regular session here; ballads, narrative songs, lyrically introspective pieces.. all to be joined in with in your definition Banjie?
Sorry... not in a million years.
Call them singalongs if you want, but sessions are a thousand other things.
If singing along is common practice in a club it is not easy to ask others not to join in - you have immediately thrown up a barrier between the listener and the singer.
My respect for Tom Paxton has just rocketed sky-high.
The practice of singing along has attained 'bodhran' status as far as I'm concerned
Jim Carroll