I don’t give a ripe fuck if someone with whom I don’t have a close relationship addresses me as Ned or as Mr. Themapleleaf. Both are just parts of my full name, and it would be their subsequent behavior that would inform my opinion of their communication, not the form of address they use.
When I was last in Canada, I was addressed by my first name by someone in a government agency, and said civil servant also used her first name. Prior to that, I remember the same thing at a travel agency. I don’t think it made any substantial difference to our communication than if we had used our Mr. / Ms. and our surnames. It’s become common in the English-speaking world (certainly in North America) to immediately use first names with people. The idea that this is a form of “intimacy” is an arbitrary social construct. I don’t feel it that way. Intimacy is words like “darling”, physical touching, etc. A first-name basis, not so much. Times have changed. It used to be common for even friends to use surnames with each other (Sherlock Holmes and Dr. Watson, for example, they call each other Watson and Holmes respectively, not John and Sherlock, though they don’t use “Dr.” and “Mr.” with each other). We don’t do that and life goes on.
I am a strong believer in substance over form. The important thing is whether you stick to the professional topic at hand without any hidden agendas, not whether you use my first name or my last name.
I don’t see why we should make big distinctions in how we speak to different categories of people. There should be a base neutral language that you can use essentially with everyone. In fact, I am currently in the process of combatting a related custom. Many languages have something called the “plural you”. To varying degrees, you address people closer / more intimate by an actual singular (e.g. in French “tu”, in German “du”) and strangers, social superiors, or people with whom you have more of a professional relationship than a friendly one, with a plural (e.g. in French “vous”, in German “Sie” - literally “they” - even more impersonal). English used to have this too (“thou” used to be the singular and “you” the plural, but also the plural “you”), but droppeed this practice around the 17th century and now has only a universal “you”.
I hate the concept of the “plural you”, I see it as a relict of feudalism that does not belong in a progressive society. A singular pronoun should be enough for all individuals; I don’t want to address one person as if they were multiple people. I don’t like the very purposes behind the plural you, which are 1) to articulate social distance and 2) to articulate respect. For the first one, I want to talk to everyone directly, even a complete stranger, and not through a filter. For the second, I respect all honest people equally; I don’t want to have to show more respect to a certain category of people (elders, superiors at work, etc.) just because they belong in that category. Using only the singular you would simply be about egalitarianism and about being able to communicate with all your fellow citizens directly and democratically.
I now live in the Czech Republic, where the singular and plural “you” are still very much a thing. I just launched a website (and related FB and X accounts) through which I intend to promote the idea in Czech society that people should go over to a universal singular you (“ty” in Czech). It’s entirely in Czech, but for what it’s worth, here is the website.