Reporting to parents can potentially save some students from traumatic consequences later. Logistical problems with how and when to get the information out. Reporting is contrary to student development theory. Students who are 18 - 21 should be treated as adults. Reporting may unnecessarily interrupt a student's educational progress.
Schools already have the right to implement parental notification for life-threatening situations.
And arrests are already public information. Reporting would treat a subset of students differently. Students in residence halls would be disproportionately at risk for being reported. Not enough data to suggest that parental notification is effective. Parental notification would be an expensive program and might take away resources from other priorities.