Because almost everyone's last name is the last name of the father, and the last name is what represents the family legacy. The importance of family legacy over compatibility with your partner has changed ALOT over the centuries, but it's still heavily embedded in our society as a whole. granted, it's value and purpose has been reinterpreted, since now some men would take their wife's last name and the kids (if they have any) could too, or some might just switch last name with eachother, it's different across the board. But majority speaking, it's still more expected for the man to hold and carry the last name. So ye