That many children can't read shouldn't be happening since this ability is innate and learning it presents no greater difficulty than learning to eat with a spoon. Why it does is the unacknowledged "Elephant in the Room," and not the fault of teachers but of parents.
A child naturally learns the language of their country of birth. Thus one born in the U.S.A. learns English and one born in Germany learns German and the same for other countries. They accomplish this not by memorizing all combinations of words which is impossible, but by inducting the grammatical structure of their language, a task for which the human brain is genetically programmed at birth.
Thus if parents first read to and then with their toddler beginning at two years of age, aiding the reading learning process by moving their finger along the printed line, their child will read simple books upon beginning kindergarten. Not all children but nearly all, provided that they are experiencing a "good-enough" parenting since its lack can create psychological difficulties affecting learning.