Yeah, totally worth a bazillion dollars and gigantic surveillance apparatus just because Joe can't follow a simple map or ask someone in the streets how to get somewhere.
Discussion
I think first of all it is useful for commercial activities.
Although I suspect the military sector is the main reason they exist from the beginning, like many other technologies (well, the internet...).
Btw, GPS & co technically can't monitor anything, they are push-only.
An interesting stat: approximately only 1.27% (133 of 10,500) of all satellites in orbit are related to global positioning services.
GPS is used by many many many many many things, civilization would probably grind to a hold without it at this point. Also GPS is not surveillance, a gps chip/antenna just listens to pings and figures out where it is based on that