Rudolf Flesch, Why Johnny Can’t Read ? And What You Can Do About It (1955) explained it.
About 20 years later, he wrote "Why Johnny STILL can't read".
BTW, when we were homeschooling, I figured Americans were the most literate in the Victorian era.
So I looked for books teaching reading from 1830 to 1860.
I quickly found two sets of phonics rules that have been forgotten since then.
The table of substitutes and the table of silent letters.
I put them on my edsanders.com website.
Scroll down there, and look for "phonics" and click on it.
Do it soon, as I am going to be working on that site, and they may disappear for a while.
They are made to be printed out as "cheat sheets".
I see you’ve collected a lot of eclectic information on your site, including tables of phonics rules. I don’t think I have seen those before. When we were learning to read it was a blended approach in which we got Dick, Jane and Sally readers at school and a more phonic approach at home. We had a lot of spelling tests and gradually absorbed unusual spellings and pronunciation through reading, daily school work, and magazines. I remember liking the vocabulary builders in our newspaper and my parents’ Readers’ Digest magazines. We don’t seem to see those ongoing reminders to develop our vocabulary even in adulthood.