In the UK if you have a tracker fitted the police will absolutely go and check it out immediately after reporting, they are pretty efficient at it. What the thieves started doing though is they take the car to a car park several miles out and let it sit there for a week, without spoiling the thief's position - if the car is still there after a week it's good to take. A lot of tracker-fitted cars are recovered this way, they are usually found just sitting in parking lots, not in some dodgy garages.