To the surprise of many students and parents, public colleges in every state except Louisiana use for-profit debt collection agencies to recover overdue tuition, library fees and even parking ticket fines. Many universities add late fees to students' bills, and when debt collectors add another 40 percent, students can end up owing thousands of dollars more than they did originally. In some states, the law requires public colleges to use collection agencies if debts go unpaid for too long. Sam Houston State University in Huntsville, Texas, sends overdue accounts to private debt collection companies after about six months, according to...