Well I am proud of being southern. I think it is disrespectful for a child to call an adult by given name. As I said, putting the "miss" in front is a way of showing respect but more familiarity than addressing with Mrs. Or Ms. And last name. My daughter friends, bf etc called me miss shinja or mrs. Xxxxxx.
I think the ma'am is a way of addressing or answering someone in a respectful ways. Like many terms the inflection or body language can change the meaning. There were many times my teenage daughters said. " yes ma'am" and they were not thinking love and respect.
I would only use sir or ma'am to address someone when I can't think of another way to address them .. "excuse me ma'am" sounds odd. Maybe I have been out of the south too long
... Miami is not known for it's manners..
Or polite people. But it still amuses me that the students address the female teachers as " miss" ..they don't even used the last name.