It is probably personal bias, but I find this article lacking. I tutor once a week in a GED class and find there is definitely value for the students outside of the GED itself. My main responsibility is to help the students develop their math literacy. Sure, they might not use the Pythagorean theorem once they get out of class, but you can be sure that they will use the knowledge they gain about percentages the next time they buy something on sale. There are literally hundreds of examples where, IF the student takes the time to learn a concept, they will be able to apply it in their life regardless of whether or not they actually get the GED or not.

(Note: I tutor at a community center and not in a prison, so this probably changes the demographic a bit.)