Trick or Treat

Some states are trying to keep our kids safer on halloween (and what's not safe about sending your child to the door of a complete stranger begging for food). They're having all registered sex offenders report to a common location (town hall or police station) on the night of trick or treating, where they'll remain until all children are safely off the streets- approximately from 6-10:00.
I respect and commend the efforts of law enforcement to try and protect our children, but wonder just how effective their method is. According to the report I heard on the news there are no statistics that say more children are accosted by these predators on Halloween.
So why halloween? Aside from the obvious, I would think that Halloween would be the last choice for a sex offender to strike. Most kids travel in herds on halloween. I've opened my front door on many a Halloween to a small country of children chanting trick or treat with arms outstretched.
It just seems to me like kind of a lame attempt to remedy a serious problem. If these people can't be trusted around kids on Halloween, then what's to stop them from harming children on say... Flag day or Columbus day or any day for that matter?? Sounds like we need to start locking these pervs up on every holiday (or every day)... if that's the only way to keep our kids safe...