It's just the odds. The density of airplanes is a LOT smaller in areas
not near airports, airways, and VOR intersections. There is maybe one
or two midairs a YEAR not near an airport (if that). I don't have the
exact stastistics. But it is small. Near an airport, yes, there are
more collilsions. But unfortunately (and I am NOT knocking them, I wish
I had one), the devices that warn you against collision, although they
work near airports, there are SO MANY planes nearby, you pretty much
have to ignore it and use traditional techniques.