The more mundane case of reliance on GPSes is to not know the route you're taking and blindly following the GPS. Then if (for example) there's two exits close together it leads to distracted drivers, focused mostly on reading the GPS device trying to figure out which exit the GPS is telling them to exit to -- which can lead to rapid, panicked lane changes.

Source: was hit a few weeks ago by a car that did a sudden lane change with no signal right before an exit by a guy who was trying to follow his GPS...