Children have always called me by my first name and I'm fine with it.
I don't think being made to address adults as Mr/Ms So-and-So makes children respect that adult any more than if they used the adults' first names. I know there were adults I addressed "respectfully" as a child whom I thought were stupid and/or bullies etc.
When I was a kid, adults who demanded that I address them as "sir" or "ma'am," (which I wasn't required to do with my parents), just seemed like bullies. It didn't make me "respect" them more.
@Badseed exactly but most people especially those higher on the narcissistic spectrum, don't care so much about how things are, only how they look like they are.
I do not use first names unless encouraged to. At Uni, professors use first names and I still cannot seem to do it, I prefer "Prof. or Dr." My students call me "Dr.___"
@Badseed these kids are raised by authoritarian bullies. They can't breathe without permission and they can't breathe even with it. I've had a friend like that.