Anyone who thinks the additional screening is random or selected by non-airline policies (FAA/FBI) exclusively is deluded.

All you have to do to verify this is to travel a number of different airlines. All of them have a certain percentage that they separate for additional screening and yet my chances of being separated is very different in each airline.

I am "gold" elite or better in UA, AA and CO. I have never had a flight in AA where I wasn't subjected to additional screening. In UA, I have onloy been separated for additional screening once in LHR. CO is inbetween. If it was strictly random and selected by FAA/FBI alone why would I find this experience so different amongst the airlines?

In my experience, skin color/ethnicity does seem to play a larger role in AA selections than UA or CO.