"First, historically mass education of the type we now employ is only about a century old, and designed to produce factory workers..."

Or else until about 100 years ago there was no economic benefit to educating the great mass of humanity, and industrialization created a type of work for which literacy and numeracy helped.

"Learning to handle monotonous boredom and obey orders was of primary importance to a factory worker."

The education of the children--sons, mostly--of the well off always involved a lot of monotonous boredom. Orders were enforced with a stick.

But indeed kindergarten was a half day in my day. The extension of schooling to younger ages is at least partly a result of the need for day care, with more and more mothers in the work force.

"Teachers know this doesn't work, but schools are obsessed with testing and metrics to the determinant of real education."

Quite so.