I think there are cultural differences...the more or less American way that I am familiar with is to have group singing, let's sing something we all know etc. Other traditions listen respectfully to one singer. Perhaps you are from that tradition.

You are the singer. Set your rules and don't expect others to know what they are in advance. I expect people to sing along with me if they know the words, but to let me set the rhythm, melody, words etc. The singer alongs should be subservient except in cases where the person singing absolutely can not carry the tune and needs lots of help.

Just announce your preference, preferably in advance of people paying money to see you, if they pay, so they can make an informed choice.

They are not being rude, etc. They are following a different set of rules that they go by. mg