When TSAPre was first introduced, TSA asked selected US carriers (including SWA) for a list of their frequent flyer customers and those customers travel records. Based on that information, some of those frequent flyers were given pre-check either randomly, occasionally or pretty much always. This was before you could sign up for it and had to pay for it. DW and I were fortunate enough to get it back in those early days.Virtually every flight we've had in the past 6 years had been Pre. There was a 9 month period in 2014/2015 where I was dealing with an identity theft issue and the Fed's were involved. During that period of time I did not get Pre, but DW did. The ID theft issue was finally resolved (and I received a letter from the Feds telling me so). A week later I had a flight - got Pre again. I've had it on every flight since then, all of which were SWA up until our flight 2 weeks ago which was on Alaska. I was stunned to see that we both had Pre. I've never paid for it and don't have a KTN, but it appears that we are in the TSA "approved" database. Could've just been random chance, of course.
I have gone through more than 1 FBI background check in my life, though. But DW never has.
Steve