my question is, how does the driver of the vehicle not see that he is being followed, from OR to PTA.
Surely he wouldve noticed something.

I frequent the airport alot picking up and dropping off people.
Most often in times its the guys trying to help you carry your bags and somehow pretend to assist where they can.
There are more than often weird characters hanging around at the collection/pickup area.
just have to keep your eyes open all the time especially with events like these occurring more often.

As for the CPF, well done guys and/or ladies, in the westrand we promote cpfs being started, with proper structure and code of conducts, we promote cpfs establishing a working relationship with their saps station, station commanders, captains, etc, not only are you the eyes and ears, but you assist with scene control, victim support, establish relationships with medical support associations,eg, netcare, er24, which ever is closer to your area and readily available.

Also ensure your guys follow scene management training, as we learnt the hard way.
Have a victim support team as well.
Good thing to have your patrollers attend first aid training, this will help in the time while medics are on route as proved above.