people who want to sing generally want to sing well

Bryan, that is your experience, not mine or Jims. Would that not be better changed to

"MOST people who want to sing generally want to sing well, but not all are capable of doing so"

As to

as responsible adults, they can be trusted to put in the necessary work.

Are all adults responsible? Can they all be trusted? I would like to think so but in my experience it is not always the case:-(

Rather than suggest that we are incapable of grasping the concept would it not be better just to acknowledge that our experience is not the same as yours?

Cheers

DeG