Having a microphone to detect broken glass is very much not obvious. As someone completely unfamiliar with the problem space, I would have assumed the normal solsolution was something along the lines of: run a current throught the glass and check the voltage "drop".
I could see this if you connected the device to the system that monitored this. But since you never do that in the install process, I am not sure why you'd assume that's how the system would work.
