Notwithstanding deficits of empathy or understanding, popular language leaves us ill-equipped. I've worked in service, and have addressed customers by the gender titles of maam or sir, not because of a desire to define them in that way, but because there are no well-known alternatives for directly addressing someone in that situation. Language changes, but slowly and with difficulty. I'd be curious what alternatives exist to maam and sir for directly addressing a stranger in a polite way. In Chinese there is no he or she, only ta. However, strangers are addressed by gender-specific titles. I used to have long hair, and have been maam'ed on numerous occasions. Sometimes the person corrected themselves, and sometimes they didn’t. I never enjoyed it.
This is a good find Remontoire. I have already copied it to two friends - one very close friend who defines "him"self as liminal and lives in the post-gender (non-binary) world. Another, a family member, who still see the world in binary terms and very much wants to "pass." Everything depends on "passing" before moving to the next step. We will all have dinner together in March, but perhaps will go to the gaybourhood where wait staff might have more experience with the honorifics besides "ma'am/sir." Are you at McGill?