Yes, vehicle theft and hijacking rates are a lot higher in South Africa than in the US and the recovery rate for a vehicle with a tracker system is massively better than for those without.

One of the biggest risks with tracker systems is that if you're hijacked the criminals may force you to give up the unit's location if you know it, so it's been made public knowledge that when the tracking companies install one of the units (which is small enough to be hidden in many different places in a car's body) the owner is forbidden from watching it being done. So I have absolutely no idea where the tracker unit in my car is.

Most of those tracking companies then have their own helicopter fleets and armed response teams to initiate the search and recovery of the car and either back up the police when they reach the scene or perform the arrest themselves.

As an aside, the US equivalent is LoJack which operates in pretty much the same way, with the exception that LoJack signals are sent to the police, not to the tracking company's response units.