Yes, I do believe that children are diagnosed with "problems" because teachers aren't taught how to deal with "different" children - those who learn in a different manner and at a different speed than "normal" children (and I can tell you that "there ain't no such animal").
Approach the reading in a different manner - is your son interested in a particular subject? Space? Art? Mechanics? Engineering? Offer him a deal where IF he reads the books for his assignments without being reminded more than a couple of times every month or so, you'll buy him a book about the subject of his choice - let him choose the book!
And DO get him tested for ADHD. You didn't state how old your son is but I think you'll find that as soon as puberty hits, his ADHD - if that is what he has - will disappear.
I was diagnosed with ADHD at age 7, the teachers said I was “too hyper” and my mom already was diagnosed with it so I was put on pills. They influenced me and I was more withdrawn and shy than usual (according to family members). I have been on the medication since, I can’t get off I am addicted to it and I lose focus/attention without it. Losing attention is part of ADHD but I think the medication has potentially made my attention worse although I am not sure.