The problem is, in the USA nobody understands social protocol. In fact, Americans are totally ignorant of social protocol. Every female to an American is called ma'am at ANY age because Americans are not taught in primary school how to address women socially.
A young girl under the age of 18 is addressed as 'Miss'
A young un-married woman over the apparent age of 18 is addressed as 'Ms'
A younger to middle-aged married woman is addressed as Ma'am
ANY older woman who's beyond middle age is addressed as 'Madam'