Comment by justjazz: Consider the borders as the walls windows and doors to your home. Leave them unlocked and someone could just waltz in. But leave them open and you invite every cockroach and vermin to invade your home.
Editor's Note: As usual, this story really has nothing to with Mexico, except that the missing family's car was found near the border. However, the family disappeared from Fallbrook, CA, not in Mexico, and the story provides no information tying the mystery to anything involving Mexico or Mexicans, much less home pest control.