We publicize student's GPA's (whether good or bad)?
Actually we don't. We provide aggregate information to the NCAA that is required as a condition of athletic participation, so the NCAA can do oversight. We also provide information so that certain athletes can be eligible for certain academic awards. Nothing different from academic scholarship programs.
But FERPA (Education Right to Privacy) requires that the university protect the confidentiality of your academic record unless there is a legitimate academic reason or you give consent for the university to release those records. This is why your parents can't call up and get your grades in their own.