The home is necessary to install smart cat eyes?

I think it is necessary, personal experience, my family usually only children and the elderly before a period of time in the neighborhood a lot of thieves, the night also knocked on the door, straight from the installation of a smart cat's eye, no one knocked on the door, because as long as someone passes through the door that the green light will be lit, I guess the thief scared, and never knocked on the door.