I'm shocked at the comment regarding SAA's releasing the kids into the public arrivals area, as that is indeed the most vulnerable point of all. Whilst on the a/c they can't go anywhere or really get up to much.
A couple of times when my son has travelled he's been held in a secured area (not in SA) until the nominated Escort on Arrival has been identified and has signed the documents. In one case, his mother and I went together to fetch him, but because she was the only named Escort on Arrival, I was not allowed into the secure area with her. I think this is absolutely correct and made me feel very secure when he travelled as a UM.