See garciasn's sibling comment to yours.

Degree matters. A lot. Saying "it's universal" because there is some frequency everywhere is misleading. There are many country Xs that absolutely deserve to be called out as bad, because they are relatively so much worse than the best countries, or even the average ones.

My intent: "it's universal" means the correlation between girls being low-value and child marriages is universal.

Your seeming reading: "it's universal" means child marriage occurs in every country...but that is a huge tactical mistake to say, because it gets in the way of us condemning countries where the problem is much worse than in ours.

My concern is for the girls, not for scoring point for condemning countries. To actually help the girls, the article seems to provide a proven solution. So let's do more of what works.

Vs. what is the track record for major non-aligned nations (like Nigeria) implementing progressive social reforms at scale, in response to moral condemnation by foreigners? That I've heard of, not good.