I have a wonderfully thoughtful friend who is sensitive as to how to deal with transgender issues, but he has explained to me how these issues are less-than intuitive to many people, and that he recently winced when his wife referred to a transgender girl as “he.”
In all fairness, though, I can see how dealing with this issue politely can be confusing to the general public, even if these are generally nice people. Cultural awareness has to start somewhere. So, I (nicely) guide people.
Example: The other day, I was shopping for a lovely dress via the phone (the company’s website had issues). The saleslady referred to me as “Sir” even though by now my voice is, I’m told, pretty darn close to the middle of the M-to-F range not just in pitch but as to the nine basic elements that differentiate gender as to speech.
I mentioned to her that I’m transgender and that it tends to mess with my head when people call me “Sir. ” Without any objection, the saleslady acknowledged the point, and sailed right along into a discussion on the specifics of the dress. Yay!