Why are kids in school not much introuced to amazing autobiographical or philosophical works and essays?

I think every form of literature has their merits. So why do primary and secondary school mostly cover novels, and poems although not in all places. I think if a kid can understand Charles Dickens and read through Shakespeare, then they can understand Franklin, Emerson, Thoreau, Russell, etc. I mean these kids are missing some amazing literary gifts to the human race.