This was absolutely not the norm I experienced in the 2000s.

Nor I in the 2010's/2020's; I have to assume GP is either significantly older than us, or from a community with a strong cultural bubble that may be clouding their judgement.

I experienced this at an boy's prep high school in the late 90s. It really was alienating to have friends I'd known since kindergarten start to refer to me by my last name out of sheer conformity.

I did in that timeframe. To be clear, it's not "Mr Surname" but just plain "Surname". I have a lot of friends like that, "Boughter", "Mooney", etc. Not everyone, but particularly if the first name was a common one or they played sports.

I'm actually surprised you're not familiar with the practice. Think Scully from X-Files or Stifler from American Pie.

>Stifler from American Pie

I always assumed it was his first name, thanks for expanding my understanding just a little!

Not just Scully, but essentially everybody from every doctor or police procedural goes by their last name. The shows aren't called Meredith's Anatomy, Gregory, Adrian, or Theo.

It’s mostly a thing among kids heavily into sports, in my experience.

I suspect the equivalent for 90s/00s nerdy types is e-mail addresses.

I am still "squirrel" to some college friends. And think of many of my college friends and co-workers as their username.

My experience is this mostly between men and generally not as common as it used to be.

My dad is called by his surname by some of his high school pals and call some of them by surname when he's around them (but not in reference to them if he's talking to me). Thinking back to my high school days in the late 00's I can only remember athletes being called by their last name. Perhaps because of football or sports that you just have your last name on your jersey. It would be an interesting thing to understand more.

I could be regional too. I'm from the US in the midwest.

There's also the "when you say Mr. lastname, I turn around and look for my father" type of responses when using someone's last name.

a lot of the time its just a nickname. public schools in the US are huge and then when it comes to sports the athletes are visiting other schools. before i knew it id meet 12 new Jakes every year so everyone goes by nicknames or last name

theres an occasional phenomenon in the US, often referenced in sitcoms, where an individuals entire first and last name sticks as their "nickname"

In my high school (Massachusetts, USA), almost all the students went by their last names, or something related to their last names. Ashley Milford was Milf, Samantha St. Paul was Saint Paul, Ryan Leonard was Lenny, Kevin Doo was Kevin Doo, for example. I'm still my surname in my head.

I learned later that we had a reputation for being a jock school though, because we all had to play a sport each semester.

This is what we used to do, because in one friend group there would be 3 mikes and 2 steves. At some point, you have to use nicknames or last names.

Nicknames include variations like Mikey, Mickey, Mikail, Big Michael, Little Michael, Gas Station Michael, Angry Michael, Tony (obligatory wrong name your group uses because there were already too many Michaels and this Michael liked his middle name)

and Mike.

Were your "American" high schools located on some other continent?

Addressing each other by surname is something that occurs principally in the context of sports, but outside of that you'd just address someone by given name. That was the case as regards children addressing each other or teachers addressing students. Students addressing teachers, of course, would address them by Mr/Mrs/Ms. <surname>. There are some oddball cases where teachers insist their students address them by given name, though.

Also, you made me feel old.

It is also used when there's name collision

If there's five people named John in the same class in school or the same team at work, it is not uncommon for all John to go by last name.

In my circle usually people would either go by their middle name or they'd very quickly earn themselves a nickname... although now that I think about it we did use lastnames for some guys. Whatever works, really. Nobody was a stickler about how they were addressed.

The surname thing was extremely common even outside of sports at my high school.