For those who think that once you hit puberty (i.e. in girls, start your period) suddenly overnight you are a woman. Well puberty isn't as black and white as that. There are 5 stages, all of which occurs at different ages and takes time.
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https://my.clevelandclinic.org/health/articles/22192-puberty]
"The duration of puberty in girls depends on the timing of its onset; the earlier the onset of puberty the longer its duration."
So from this study if a girl starts her period earlier, she would have completed her puberty around the same time as those who had theirs later.
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https://pubmed.ncbi.nlm.nih.gov/9386670/]
If you want to back Muslims up into a corner and force them to confirm that they would give their 6/9 year old daughters hand in marriage to an older man, first you must ask yourself...what 6/9 year old wants to get married? (if let's say their parents approve?)
That is why when males and females are addressed in the Quran, we know when its referring to adults because often it is paired with characteristics such as 'hypocrite', 'believing/disbelieving', 'polytheists', 'chaste', and in the context of committing transgressions or charity. What child can comprehend its message or understand adult concepts and responsibilities that comes with marriage?
We know children do not have the sound judgement therefore aren't made accountable for their wrongdoings.
All religions aren't free from corruption, child abuse isn't new, this agenda of the past has continued to the present day. Using hadiths and under the guise of "God's guidance" to justify the evil desires of man.