Why are teachers warned to never be alone with students?

It's most likely due to all the teachers in the news who sleep with their students and then A. lose their job, B. lose their teaching license, and C. end up being labeled sex offenders (unless your a hot blond haired female teacher who is according to our stupid society "unable to rape a male student or take advantage of him"). As a result teachers can't touch students or be alone with them due the worry that parents/students will accuse them of sexual molestation or rape. It's the bad teachers that ruin it for all the good ones out there.