There is plenty of blame to go around on everyone in this story.

Clearly the school and the policy of social promotion. Promoting kids to keep up with other kids their age ensures that they will never be able to learn anything. And given that clearly the majority of the kids in this school learned nothing you have set up everyone for failure. This is another one of those 'unintended' consequences of affirmative action type policies.

Also the mother has some share in the blame. She puts it all on the school but much of it rests on her, primarily for being a single mother of THREE children. Sure she works three jobs but she would be better off if she was in a relationship with the father (s?) of her children to raise them. Now because of her irresponsibility he children will be more or less drains on the state, and she is not unique, clearly this is the norm for her community.

And of course the kid is to blame as well. No discipline, no values. 272 absences over the years. He was out of school more than in. That starts in the home.