These numbers are inexcusable on the part of the parents.
Well, yes, in general, they are. I can't say with any certainty about countries outside the U.S., but I have a suspicion this pretty much holds true everywhere: most of the people who are poor today come from families who have been poor for generations. They know no other way of living. They have always been on the fringes of society, and believe that they always will be. Only a minority realize that education is the way out. Most of the parents had difficulty in school, are not surprised when their children do, and even if they think of trying to improve their child's school performance, often aren't able to. Not all, but a lot, have the attitude, "Take my child and make him learn; expect no reinforcement from me". Parents who were not read to, or who never learned to read very well themselves, are not likely to read to their own children.
Okay, that was attitude. Now, poverty itself. Remember the three basic needs? Food, clothing, and shelter. When every day brings uncertainty about having enough of any of these, it is not surprising that academics don't even make it onto a parent's priority list. For convenience, I will say that there are two kinds of poor people: the ones on welfare, and the ones who have just barely too much income to qualify for welfare--and in my opinion this latter group is worse off.
The ones on welfare usually have subsidized rent, utilities, and get food stamps and a medical-treatment card.
The food stamps are set to a bare minimum--a lot of peanut butter and macaroni meals. The cash is also a bare minimum, which means clothes come from the charity shops, or the dollar store at best--and their classmates know it.
If a kid comes to school hungry, cold because their utilities were shut off, or still shaking from the fight between their parents, they are not going to be concentrating on their school work. Lack of the three basics causes enough stress to drop one's tolerance level pretty low, usually.
The working poor can really have it rough. They live paycheck to paycheck, and any unexpected expense often means they'll have to do without something--and often, it is something they need, such as a balanced diet, or heat. A car or refrigerator breakdown is a catastrophe. They might well get evicted. These parents are not likely to be going over their children's homework, if they are facing a crisis--which they can be, 'most any day. I still remember this 7-year-old girl who, though I had addressed "What kind of work do you do?" to her mother, responded with wrinkled nose, "She takes off her top and dances on tables." Mom did have the grace to look embarrassed, and said simply, "The money's good".
All of this did not even include addiction. I don't need to go into detail on spending the rent money. I will add a story, however. A school social worker I once knew was so depressed one day; she had done a magnificent job the day before of taking a young mother to the grocery on check day (when the welfare check arrived in the mail), and shown her that it is economical to buy large amounts of meat that's on sale. Then she'd gone home with the mother and shown her how to divide it into meal-sized portions and freeze them. She learned that, the next day, the mother had sold these portions for whatever anybody would give her, so she could buy drugs.
