Back in the medieval ages when a woman was married to a man, they were basically considered property for my understanding and treated like an extension of the man’s person and family. So it was customary for women to take the man’s last name since they were being joined to his family. But now here in the 21st century women are fully independent and last names don’t really seem to mean much of anything. I mean what is Smith or McGregor or any last name really mean anymore? Especially in the digital age, lots of people have digital usernames like SarahSmith1727373. So the last name clearly doesn’t mean much anymore… Which leads me to wonder, why do the majority of women still take the man’s last name? Especially when some of them have a horrible last name? I have seen some butt ass ugly last names recently, like Fink, Weimer, Slotsky/Slotsky, Hiscock (no joke this is a last name), Hardman… And then you hear the woman’s name and it’s like something way more reasonable and less stupid sounding like Kingman, or Harrison, Walls, etc.
Can’t speak for all women, but I (and I imagine some others) changed my name because I knew I’d be having kids and didn’t want there to be any confusion. Like, if I’m traveling internationally or if my kid ends up in the hospital, I don’t want one of us having to fish out a birth certificate to prove we’re both the parents. Also I’m of the percent that absolutely hated my long last name so the chance for my name to be shorter and nicer was a no brainer.
I think this is a big reason. Having a common family name helps solidify the family as a unit.
In several countries it’s simply not possible, and the family bonds are strong as elsewhere, if not stronger. China for example, family is above everything there, and you can’t change names under any circumstances.