The police definitely fouled up on this one, in that their GPS was only good for a general area, and they could not narrow it down to a single vehicle.
Importantly, just a few days ago, there was an armed robbery of a drug store in NYC, for Oxycontin, and along with the drugs the robber was given a pill bottle with a GPS transmitter in it. *Just* the robber was caught, some 30 blocks away, then he threw down on the police so they killed him.
And in the article they mentioned that this technique has been successfully used some 100 times across the US. Which means that GPS *was* able to narrow down to just one vehicle or residence.
It was like they were lacking the close quarters tracking capability, and only knew the general vicinity that their eye in the sky was telling them.
Consumer model GPS units are only accurate down to around a few meters in optimal conditions and the conditions are rarely optimal.
Anytime you are close to buildings trees power lines etc. the accuracy can fluctuate widely...
Military grade units I am sure are a different matter...