THE ORIGINAL EARLY WARNING SYSTEM
Before alarms or any sort of fancy detection gear was invented, field optics were the original early warning system. If you happened to be looking through your binoculars, you could spot an intruder hundreds of yards away, and more or less determine his intent from afar. Contrast this with the same intruder approaching within a hundred or even fifty meters of your position, and having to make a decision on his intent from that distance.
The simple fact is, field optics buy you time. In a disaster situation, even rudimentary field optics buy you enough time to determine from a long ways off whether that refugee is armed or not, or how many people are in that car that’s driving up your street, or even whether that youth has something in his hand (a weapon?). The further off you can see with your field optics, the more information you have, in some cases, many minutes before you would otherwise have the same information with the unaided eye.