LOL, some places, such as the American South, it has become a habitual sign of respect for strangers to say Sir/ Ma'am.

I recall being in South Carolina 2 years ago, a farmhouse belonging to an elderly, black friend of mine. The young, very white repairman (plumber) came in to fix something, and continually deferred to my black friend as Ma'am in a truly respectful, deferencial tone.

Like the saying goes: We've come a long way, baby!!