I can only speak for the Met Police in London!
We only have the Tracker systems installed in our cars. This only allows us to track cars equipped with Tracker systems fitted.
We will track any car with any tracking device, but this is done via our control room who relays info to us of the cars current location via our radios. There is a time delay on this as the systems they use have been bounced in outer space a couple of times and with the delay in the relay of information, we are always playing catch up.
With Tracker, it's direct, real time direct to our car so it's far more accurate and precise!