After someone has reached puberty, they can’t really be considered a “child” anymore. Would you really consider a 12 year old a child? I would consider them adolescents or young adults. Some girls mature early and look much older. I was 16 and looked a few years younger than my 11 year old cousin.
Because times have changed and it takes people a long time to finish their education, and the fact that girls aim to get educated, the thought of thinking about marriage at young ages is disturbing to some. But somebody from a diff generation would not see this. Both my grandmothers got married in their early teens. I am sure many people’s grandmother got married around that age. A friend of my mom’s got married at 15, so it was only a generation ago. so people from around that time will not see a problem with this. As the current aunty generation ages a little, this won’t be as common anymore.
I know the bit in bold is true Islamically but some of us reached puberty v.early (in my case it was 9), don’t think it’s wise to use puberty as a blanket indicator as to whether a person is emotionally mature enough to make sound decisions or take on ‘adult’ responsibilities..