It's actually a very reasonable assumption, as most people don't really know about the limits of fiber, but they do own mobile phones which seem to work almost wherever they are thanks to wireless technology.
"Normal" people don't know that kinda stuff.. Let's be honest, they make many of their assumptions from TV and Movies - and often those disaster movies focus on the world grinding to a halt because "the satellite network is down" (I do the same with other industries!)
