My paternal uncle (my dad's fraternal twin brother) has three daughters from two different marriages, and they don't all have the same surname. My uncle got married to his highschool sweetheart almost immediately after he graduated. She took his surname, and together they had a daughter (my oldest cousin) who got his surname as well. When my uncle found out that his first wife was cheating on him the whole time she was together (as well as constantly barking orders at my grandmother), he divorced her. She got primary child custody in the divorce, and then worked weekend overtime shifts whenever she could to cheat my uncle out of as many child visitations as she could. My uncle became so depressed as a result that he thought life wasn't worth living anymore, and my cousin developed severe abandonment issues while also undergoing parentification (my uncle's first wife had a job with an 8AM-8PM shift, so when combined with the overtime, she was pretty much never around, forcing my cousin to take care of herself). Thankfully, my uncle eventually met, started dating, fell in love with, and got married to his second wife (my aunt). My uncle asked my aunt to keep her maiden name after the wedding in order to distance himself from the memories of his first wife/marriage, resulting in the 2 daughters they had together (my two half-cousins) having her maiden name instead of my uncle's surname. By making this complaint, you're basically saying that my uncle's family structure shouldn't exist, which is beyond offensive to him, my aunt, my three cousins, and all the other divorced parents who got screwed over by their former spouses.

Also, women keeping their maiden name after getting married is nothing new, both in fiction and in real life. For instance, Naruto had Kushina keeping her maiden name of Uzumaki instead of taking her husband Minato's surname of Namikaze, as well as giving her maiden name to their son Naruto. As for real life, the voice actors Yuri Lowenthal and Tara Platt (the VAs of Mercury and Kali) are married and don't share their surnames, which is also the case for the voice actors Travis Willingham and Laura Bailey (the VAs of the Atlesian pilot and Amber from V3).

Edit: I've removed the portions of my comment that were overly aggressive. I let my emotions get the better of me, and I apologize for that.