In reflecting on the history of formal education, it's necessry to separate the Oxbride tradition of grooming future aristocrats and nobles from the rise of compulsory public education at the end of the 19th century, which is a responds to a variety of challenges raised by both industrialization and modern cities.

For a retrospective review of that history, with extensive citations, Ivan Illich's Deschooling Society can get you started on your own research. His book is fundamentally polemical because he was invested in his opinions about the past, the present, and the future, but the bibliography and citations prove useful for this topic even if you don't buy his summary perspective.

There are of course many other primary and secondary treatments contemporary to the time, that you can review without reading through Illich's polemics, some of which are very easy to find in the Harper's Magazine archives.

What you'll find, broadly, os that there was very little said of the idealism we now attribute to enlightment and almost all of the dialog about modern public education, especially compulsory -- by both proponets and critics -- was quite practical, focused on what schooling and education would acheive (or sacrifice) for industry, social cohesion, cultural diversity/uniformity, crime, child welfare, political alignment, and national identity.

IOW, "I've never seen any evidence" is understandable (we each only have so much time to study), but it's not for some lack of that evidence.