I agree with everyone who says that informality comes with age.
But I do notice regional/cultural differences, and differences along the lines of status.
Taking status first, I took my degrees at Ireland's oldest university, Trinity College Dublin, which is considered to be on a par with Oxford and Cambridge (it's the only other university whose degrees Oxbridge considers equivalent to its own. Snooty or what?
). Anyway, all lecturers had to be addressed as Dr, Professor, Mr, Ms (as their appropriate title may be). There was no informality permitted between students and academics. If academics bothered to know the name of a student, they would usually use first names, but I was persistently called 'Miss Richards' (never Ms) by a couple of older academics. It was quite a rite of passage when one lecturer, who'd become a sort of mentor to me in my last two years - and went on to become my PhD supervisor - told me after I'd graduated from my first degree to use his first name. (I'll add that it took me a further two years to call him anything at all, because I felt so uncomfortable about using his first name and he frowned if I called him Dr Surname :p ).
Then I moved to the UK to teach at Keele University, where informality is the custom. All students call academics by their first names. Most students take to it very easily but, as Metwin1 says, students from the Far East did not - they almost all refused to use first names alone and it was all we could do to stop them calling us Dr Richards, Mr Smith or whatever. So I got very used to being Mrs Wendy (they didn't seem to understand that many women prefer Ms, and the idea that I had a PhD didn't quite seem to enter their thinking
). I also had a British mature student just out of the army after 24 years; he found the informality extremely difficult to take, so other than when we were talking alone in my office, for example, I was 'Doc' or Dr Richards.
Now, the regional difference I've noticed since moving to Canada is in dealing with people I haven't met before and arranging business over the phone. Say, making a dental appointment or ordering something to be delivered: the person on the other end of the line, having asked my name, will call me Wendy throughout the conversation, where in the UK I'd be used to being addressed formally. I hasten to add that it doesn't bother me in the slightest and that now I'm getting used to it I like it.
As for the original point of Anna's question - yes, the internet is the great leveller. I've chatted to many people without even having an idea of their ages, and in many cases ended up very surprised.
I've met a 16-year-old FoLC and wouldn't for one second have expected her to address me as Dr Richards!
But then, I don't expect the children of friends to address me formally either.
Wendy
(who probably needs to start thinking about whether she expects her new niece to use 'Aunt' or not... )
