Here is a first-hand account of getting Pre-Check in the name of expediency. Are TSA procedures not about keeping us safe? From the author:
"Of course, deep down we all knew this already. The TSA is not about keeping us safe, nor is it about apprehending would-be terrorists. The TSA serves one purpose and one purpose only: To create the illusion of safety, the perception that someone is in charge and taking care of things, even if any sensible person can see that it’s all a charade."
Anecdotally, I've heard of this happening at other times and places. Proof that it is all security theater for those paying attention.