That could explain it _today_ and recently, like _my_ lifetime.
But for the history, the origin of the "whole word"/whatever method, we're talking OG Progressives, the ones who had to relabel themselves as liberals after Wilson's frank fascism in WWI ruined the brand.
Stuff that happened in the 1920s and I think earlier, not something I could ask my parents about, their being born after the 1930 publication of that first basal reader. Given the poverty of the times, they probably learned using older books anyway.
Note also in this period the Progressives were quite the fans of eugenics, Jim Crow and segregation ruled much of the US, so that large cohort of -1SD 85 mean IQ negro students weren't in white classrooms by and large.
Instead, as I understand it they were taught mostly by their own "talented tenth" and a lot of them _did_ learn how to read. Heck, even those Haitians who couldn't "get" alphabetized sorting of files could still read and write the words in them....
And troublemakers were dealt with, one way or another. Corporal punishment was all but unquestioned I'm pretty sure. Expulsions, I don't know. Short bus, ditto. Might be fewer of them simply because of later medical advances, including antibiotics only starting for the US civilian population in 1946.