Just a few companies accept the challenge to raise a system anti-intrusion, or outer alarm in an installation.
There are few companies that speak openly about false alarms.
A system anti-intrusion, or outer alarm, is not for anything similar to an inner alarm system.
The main reason to all those questions, resides in the complexity of these systems. The outer, much more complex sensors and more are technologically advanced; simultaneously that must be immune to the meteorological changes by very aggressive which they are (rain, snow, fog, wind...).
An outer sensor, must be able to distinguish a dog, a hare, an eagle, an owl, a leaf, a plant, and evidently of a thief or intruder. It is not just like one alarm of interior. Then with one it alarms interior, everything what one moves in his reach, must make sound the siren.