I found this podcast from this 
post:
I subbed today for a 7th and 8th grade teacher. I’m not exaggerating when I say at least 50% of the students were at a 2nd grade reading level. The students were to spend the class time filling out an “all about me” worksheet, what’s your name, favorite color, favorite food etc. I was asked 20 times today “what is this word?”. Movie. Excited. Trait. “How do I spell race car driver?”
I've only listened to one episode so far, but it's really well produced, seems well-researched and very well put together.
From what I gather so far, the ways that the American public school system "teaches" kids how to read is not only completely wrong, but actually saddles them bad habits which fundamentally hinder their reading comprehension.
A huge swath of American adults are functionally illiterate, and I think I'm starting to understand why.
That probably helps on some level, but from listening to the first two episodes of the podcast, the problem seems to be that a lot of kids are being taught a fundamentally incorrect method of how to decode written language that's making it much harder for them to read that it otherwise should be, and often leaves them completely unable to parse new words. Like, if you gave them a word they'd never seen written down before (especially if the word is by itself, devoid of any context), they wouldn't know how to pronounce it, even if they've heard the word spoken before.
So simply having books available won't actually help (most of) them, because they just don't have the skills necessary to figure out how to decode written language, or how to connect written language to spoken language. They need to be taught the correct way of reading first.
(Of course, once kids finally have an understanding of the fundamentals of how to decode written language, having tons of books available to read so that they can further practice those skills would definitely be a massive help for improving literacy.)
I haven't listened to the podcast but English as the language theyre learning has gotta add a whole other level of difficulty. Like Spanish you know the vowel sounds are all the same, Norwegian updates their spelling so that it always matches the actual pronunciation, Korean literally puts how to say the word symbolically in each part of a character, Japanese hiragana and katakana is always the same, Cree syllabics are one-to-one (although it was designed that way intentionally), the only other ones that'd be hard is like Chinese or Japanese Kanji and stuff like that but those usually have a pronounciation hint character/radicle in their as well.
English is like that but with wildly different rules on top of bad pedagogy, yikes.
Despite English's weird spellings and exceptions, there aren't that many different sounds and there is a very effective way to teach how those sounds correlate to written words. It's just that no one used that method for like 30 years because it was "too old fashioned".