How do people not have a last name? It doesn't many any sense at all. When you are born you are given and first and last name (family name).
Without a last name it makes it impossible to track or locate any family members, so strange.
Quite common in some cultures. In some places in Europe wasn't universal before Napoleon, whose administrations in occupied countries instituted a lot of reforms. (And in a lot of cases just formalized what had been informal 'son of' usages before, but thereafter fixed).