What I think is a major issue is that the UN "human rights" document says that schooling is mandatory and must teach about the UN (yep! it is a "human right" to be indoctrinated)

I noticed then that several governments to please the UN (and get their precious IMF money and whatnot) will then game the stats as needed.

I am from Brazil, here the public schools after UN meddling got in the picture first went the route OP said, but the UN didn't rated the country education based on scores, but based on dropouts, the more dropouts you have the worse your score is.

So solution is not have dropouts! Cue government doing two things:

1. Banning any possible form of homeschooling.

2. Making a law where you can't fail a kid, even if the kid is completely retarded and just drools all day, as long the kid in question can write their own name (even if they don't understand the meaning or treat it just as a drawing), they will pass...

3. Convince the population that avoiding dropouts is important, the government regularly runs massive marketing programs (doesn't even matter if government is left or right) saying how important it is for kids to finish school, and how great it is that now that they can't fail, they don't drop out.