Because we have established "real" fences are teh suck.
Link.
Link.
I hope it sounds like the bell when I walk into 7-11, that would be awesome.The 28-mile virtual fence includes 98-foot unmanned surveillance towers that are equipped with an array of sophisticated technology including radar, sensor devices and cameras capable of distinguishing people from cattle at a distance of about 10 miles. The cameras are powerful enough to tell group sizes and whether people are carrying backpacks that may contain weapons and or drugs.