Turmoil over Facebook Privacy

My senior year of high school I was a belle guard, which was an escort for the drill team.  I was always hanging out with the drill team girls which means I heard all of the latest gossip.  In Spring of my senior year, some of my friends got themselves into some deep trouble because their lack of Facebook privacy.  One of juniors on the drill team sent pictures of six senior members drinking alcohol to the principal.  The drill team has a strict no drinking policy and when the principal told the drill team director about the picture, trouble ensued.  The girls were called into the principals office five of the girls admitted that there was alcohol in their cup while the sixth denied it.  So surprisingly the five girls who owned up to their mistake were suspended from the drill team for six weeks, missing multiple performances and contests.  The sixth girl who denied drinking alcohol got away without any punishment.  The whole point of the story is that these girls did not have their Facebook page set to private.  Because of their lack of common sense, their perfect senior year went horribly wrong.  It blows my mind that such a simple error on their part ended up hurting them so much.  Internet privacy is a very serious matter and if people aren't careful they can mess up their lives.  I feel that it was unfair to the girls that owned up to their mistakes got the full punishment while the liar got away.  Does anybody else feel this way or have a different opinion about the situation?  This incident is what really opened my eyes to internet privacy.