Nothing of value is taught? Well let's see, a young lady by the name of Valencia might disagree. Kids who walk across the stage with a 5.0 and receive academic scholarships might disagree. Kids who leave GC and become doctors, nurses, lawyers and research scientists might disagree. Kids who while in High School can receive college credits and save money on tuition for their folks might disagree. Kids who learn to build homes, repair cars and weld steel while in high school might disagree.
Your comment might be more appropriate if you said, kids who have no desire to become something or who have parents that don't value education are the victims of bad fruit of the tree of public education.
There will always be one thing wrong with your theory worker A. Many kids succeed with the same teachers, the same classes, etc..... When you can explain that, get back to us on your theory.