Even in the informal, everyone-is-equal world of today, first names and last names are still used as indicators of status. This struck me most recently when flying home from Venice. The captain did the usual welcome announcement once we’d all boarded the plane. He referred to himself and his co-pilot by first name and surname, yet introduced the cabin crew by first name only. Why? I assume because pilots are considered more senior in rank, hence ‘better’ than cabin crew. But in fact these two professions are just different – it doesn't make any sense to compare seniority across the two.
The same applies to the health professions. Doctors are referred to by surname and nurses by first name. In the past, of course, nurses were also referred to by surname – back when everyone was known by their title and surname in the workplace. So why have things changed for nurses, but not for doctors? Again, I assume it is to do with perceived seniority. I remember my surprise when the doctor who was called to assist with the delivery of my first child introduced herself by her first name. Even after hours of labour, this struck me as unusual! When the midwives told me that this doctor was coming to assist, they described her as ‘lovely’. She was also young. Maybe that’s why she bucked the naming convention. Or maybe she was keen to establish a rapport with her patients quickly. Either way, this is not the norm.
Some of my elderly relatives lament the fact that it is now usual to call someone by their first name rather than their surname. One of them mentioned this in the context of being a patient in hospital. Now all patients are referred to by first name, whereas in the past they would have been referred to by title and surname. My elderly relative found it demeaning that someone sixty years her junior should address her by her first name.
So, in the past, surnames were the norm outside one's circle of family and friends. But nowadays first names are the norm, except in professions which are considered particularly prestigious or in some way special. It's interesting how these things change.