The cost of educating 1 child was never lower than when they were taught by their parents how to work the fields while doing said work. Education costs tell us very little about both quality and efficiency of education.

Most of that is just babysitting / baby jailing cost.

Well the thing with education is that there is always more to learn since knowledge keeps increasing. So arguably what you want to measure is productivity. Has television, say PBS increased educational productivity. I would say yes. I remember watching Nova shows in science class and so forth. So yes TV has reduced costs.

Books also increased productivity in the same way.

Would remote learning reduce costs? Yes.

Will AI systems reduce cost, yes.

Do you mean education as in actually education? Then the cost has fallen to basically nothing. Or do you mean education as in credentialing, which is the way most people use the word? In that case it hasn't because, as the value of a credential rests entirely on other people not having it, it is in the interest of schools to restrict the supply.

Unequivocally yes. Not every usage of a screen in education is beneficial.

But there are absolutely numerous use cases where being able to display graphics on a screen (or even better interactively) is a massive benefit. Think of any sort of science that's better shown with animation than just a static image on a page for example.