I find this incredibly hard to believe. I suppose it depends on your age but I’m early 40’s and had many of my friends since teenage years. Kinda hard not to learn someone’s surname after that amount of time.
Not to mention I used to be on social media in the early days and so surnames were a thing there.
Easy, meet various guys in pub, chat every few weeks, repeat for 30 years. Noone ever suggests adding each other on Facebook. Actually I know very little about them, but if we're both there at the same time we'll talk about nothing for hours.
many at some point I recall reading their last names somewhere. but you never used it and as a result if you ask me I really cannot even guess almost any one of their surenames. and these are people I hang out with irl on weekly/monthly basis. I find it funny