why the male's last name?

I think its because years ago it was seen that when a couple married the woman "belonged" to that man it is HIS family therefore his name given to all. I dont really see it as a problem me and my partner are not married (we plan to) but our children have his surname he is their father they dserve his surname my opnion on the matter probably has more to do with how I was brought up than anything else though i suppose its different depending on what is seen as normal while you were growing up for us it was that the children born into a family were given their fathers last name even if they were not married.

A family name or last name indicates the family to which the person belongs. The use of family names is widespread in cultures around the world. Each culture has its own rules as to how these names are applied and used. But generally in the past, women belonged to their husbands. A man would buy a daughter for livestock or money. Daughters would be paired off with another family for wealth or status that it would bring. It is all about ownership! Luckily those days are long gone in most societys today!

The man is the head of household in Biblical terms. I don't know about other countries but America is very Biblical oriented because of the pilgrims, at least that is my thought on the matter.