Why surname alphabetic is followed in Directories instead of name alphabetic?

Question

I think Name alphabetic order is more user friendly. Is there any definite preferred logic for the Surname alphabetic system ? Anyone knowing the history of this usage?

Answer 1

I don't have authentic information. I feel this is because of the multiplicity of common first names compared to surnames.

Ages ago, the population in a community would have been small, making it easy to identity people with their first names. As time passed, there might have been more people with the same first name, and so they added a surname. With improvement in movement of people and better communications, identification by first names also became somewhat difficult.
Even after adding surname, identification might have become time consuming, and so a second name was added. (In some countries, the second name is that of the father of a person or the husband's name, if it is a married woman.)
I suppose even today, with all the three names people may be given, it still is easier to locate one from an alphabetical listing of surnames than from first names!