That sounds like something different (or maybe the airline lets random people into TSA Pre-check?). This is the service people are talking about: http://www.tsa.gov/tsa-precheck.
You pay $85, and the government basically does a background check on you. If you pass the background check, you are in TSA Pre-check.
> That sounds like something different (or maybe the airline lets random people into TSA Pre-check?).
It is not something different, but I think some airlines do automatically sign some of their clients up for pre-check, particularly if those clients have status. E.g., United Airline's pre-check information page discusses people who have opted-in through their frequent-flier program:
You pay $85, and the government basically does a background check on you. If you pass the background check, you are in TSA Pre-check.