I didn't get a sense the article singled out charter schools specifically rather it just lists it as a alternative place that funds get funneled instead of to neighborhood public schools.
Which brings me to:
> The main reason "private" (in their sense of the word) schools are gaining in popularity is precisely because they are seen as delivering a better education by an ever wider chunk of society.
If you accept that the article is talking about charter schools, then yes, perhaps the narrow focus of the charter could allow for a stronger education in a specialized area could allow for better education in that area.
But, if you accept it as private schools as a whole, then I don't buy that argument fully. The administration has been very clear that the motivation is "anti-woke" and "traditional family values" and nothing to do with education quality. In fact, as someone who went to a religious school in a small town (granted 30+ years ago) I can vouch that my education (especially in science and math) was FAR worse than the public schools at the time and homeschooling quality varies wildly.
Edit: As far as
> More specifically the US currently spends more than the vast majority of the world per pupil
I also find this focus on spending per pupil very odd because it doesn't account for cost of living.
And if you dive into the fine print it says:
> Includes both government and private expenditures.
So what if (and this is a completely untested hypothesis) the reason we spend so much per pupil in that chart is being exasperated by the private school system.
Edit 2: after diving into it, that source provided is greatly inflated by private school spending including private colleges (which are insanely expensive). So that same data can also be used to argue the US is really spending too much on private schools not public ones.