I was travelling from Johannesburg to Paris on EgyptAir recently and at check-in in Johannesburg was subjected to a barrage of questions about where I lived, what I was doing in France and how long I had lived there and my documents were inspected by three different people. The most intriguing question of all was when they asked me if I was travelling with X who I was indeed travelling with. X was also asked if he was travelling with me and was asked to point me out at his check-in counter.
How did the airline know we were travelling together as we had bought our plane tickets separately, using different credit cards and different computers from different locations? The only thing that I can think of is that we bought the tickets at about the same time (talking over the phone) and chose adjoining seats on all our flights but is this really used to link travelers? And is this linked to the intense questioning we received?