Many of the wonderful purposes served by GPS are applications that were
impossible before GPS existed. Organizations that depend on these
applications are necessarily dependent on GPS; they cannot be otherwise.
Suggesting that they somehow find a way to do without something that
cannot be done without is illogical.
If ease, cheapness, or speed are of the essence of the communications
application, then the application is dependent on GPS, and there can be
no backup.
GPS navigation.
You have yet to describe a single action carried out by terrorists that
would be definitively prevented by shutting off GPS. And the burden of
proof is upon you.
There is little that can't operate without the beating of your heart.