Good point. I'd also add that in the States, where the class system is more fluid (no hereditary titles), we don't even think about social rank when using "sir" or "ma'am."
Here in Italy we don't have hereditary titles as well (we discarded them when we became a republic), so I don't think about social ranks when using courtesy forms as signore/signora
. (Well, some people still insist on being addressed by their ancient titles: usually they are laughed in their face by us commoners.)
When speaking English, on the other hand, the subtext is present in my mind. Funny that. Maybe because of the perception of (British) English as being the language of a country where nobility titles are still in use. I dunno.