I’d agree that it’s ethically wrong. As to mom,child having different last name, mom may never have changed her maiden name, but chooses to have the children’s last name after dad. [You know, there are women with careers who use their name in business and a change in last name can cause their clients not to find them. Doctors/Lawyers, etc. I know one family where this is the case. I’m not saying that’s the case here, but it does happen.]
Yes, many married women do keep their maiden names or at least do so in professional dealings. I just noticed there was no mention of a father in the article.