The impression I get from some people I know with PhDs (or equivalent from schools that use different names) is that, in a non-academic/research setting, they feel that emphasizing their degree can come across as a sort of superior attitude working alongside a lot of talented people with various degrees (or lack thereof)—especially to the degree that whatever their thesis was in however many years ago may have next to nothing with what they do today.

I have no particular stake in the question though. Totally understand that people are proud of their achievement.

Yeah certainly, and even at university most lecturers I had I think were 'just call me (first name)'.

I just meant that I can't think of anything else at that level that we don't use (sometimes/to the same not-100% extent) an honourific for. In many countries (not North America I know) medicine is a lesser qualification (Bachelor of each Medicine & Surgery, MBBS or BMBS) but we still use it, so it seemed to me the argument up thread works there (Masters aren't called doctors) but not as far as I can think of anything at PhD level?

I don't think so. As you say, not any sort of Masters degree. And even though the standard JD for lawyers has "doctor" in it, no one calls anyone with a standard 3 year law degree "doctor." Obviously there are aristocratic and clerical titles as well--in addition to various certifications (though those don't usually have a prefix-type title--mostly positions like Judge do).

>Yeah certainly, and even at university most lecturers I had I think were 'just call me (first name)'.

Of course not all lecturers have doctorates and you also get into the very academia "Professor" sensitivity.