Surnames came from aristocrats, who were often more or less known for their family lineage, while commoners used to lack surnames. "Do you know whose son I am?!" an angry young boy from a noble family might have shouted.

Now commoners have surnames too, but outside of a few rich/famous/powerful families, your surname is not very useful. In other words, we have surnames, but they are largely useless.

IMHO, it would be more helpful if instead of surnames we used a "home country+home city" string. For example, a girl named Misaki, who lives in France's capital city, would be called "Misaki France-Paris". Then you wouldn't be surpised to learn that she can't speak one word of Japanese, but is fluent in French