In Israel, they always say something like, "I ask you this question because there have been cases in which someone was carrying a bomb..." Or they will ask, "Do you know why I am asking you this question?"

One of my snarkier friends once said, "No, I have no idea."
She's charming enough, and Israelis have a certain patience for sarcasm at the airport, so she wasn't hassled.

The ICTS/FIS etc. contract agents often ask the questions so quickly and carelessly that it would almost be hard to answer in a way that would arouse suspicion. They also tend to ask "yes" or "no" questions rather than the free-form responses expected in Israel.

In the case of Lockerbie, the Pan Am "Alert" agents did not speak enough English to understand passengers' responses to their questions. And it was reported in Rodney Wallis' book on the subject that they didn't even know what a selectee was. They just picked people at random.

Prior to 2001, the US had all kinds of absurd systems, like answering "yes" or "no" questions on check-in kiosks, or pointing "yes" or "no" on laminated placards. I cannot fathom how that had anything to do with security. It was a crazy law implemented after TWA 800, which--of course--was not related to terrorism. I am glad that the US finally got rid of that silly requirement. I do think that BA still asks in the United States, but it's been a while since I've flown them. Otherwise, it's only El Al for flights leaving the US.

Indeed I remember the incredibly tight security in London after Lockerbie. I was flying from Gatwick to Newark, and I remember stern, extensive, and intimidating questions.