I'm not sure. They don't have those at my home airport, but my vague understanding is that in some situations like this, the airline is paying the TSA to staff

I'm not sure. They don't have those at my home airport, but my vague understanding is that in some situations like this, the airline is paying the TSA to staff another lane for their preferred customers. To me, this seems more reasonable. Personally, I have been annoyed by a bunch of Clear people cutting in front of me in the regular Precheck line when I was running late for a flight. In private aviation, you pay a fairly big fee for TSA in some circumstances depending on the size of the plane, and you pay a fee for customs to come to the private terminal. If they were in their own line paid for by the airline, I wouldn't have been annoyed, but when it's the same screening checkpoint that we both paid the same tax for, I don't see why they should be allowed to go in front of me.