I am not sure this is in fact spying. All one has to do is to turn off their cell phone when they feel they are in an area they shouldn't be in.
I have Low Jack on my car to track it if it is stolen. It is not that people are being spied on without their knowledge, same with our PC, we leave tracks every where we go.
Throw away phones are used by the crooks, $8.00 for the phone and a calling card for $10.00
These tracking divices on a cell phone have saved many lives, lost people found and the body's of loved ones.
More then one way to look at this problem.