Thought I would share my recent Global Entry experience since I found it so interesting.
We landed from Paris at JFK and everyone was race-walking down the endless concourse towards immigration. Honestly the walk was so long they had signs posted telling you it's still 10 minutes, now it's 6 minutes, now you're almost there get into the appropriate line.
The Global Entry section was full of machines that look like ATMs, and was empty. We picked two side by side and started the process. They didn't want a passport, or fingerprints, or a Global Entry card. They want to take your picture. There's an outline on the screen and you position yourself in it so it frames you at about the shoulders. It takes a picture, asks you if you like it, and then prints it on a small piece of thermal paper.
You take this insignificant document to a guard who looks at it and ... sends you to get your bags! No interrogation, no checking documents, no "how much stuff did you buy." Just waved us into the US of A. It was the damndest thing. Obviously behind the scenes there are layers of databases sharing and comparing info, but it's all invisible to the traveler.
Come to think of it, had a similar boarding experience once at Delta. Didn't care about my boarding pass, had me look into a video camera and the green light went off. I think it's kinda creepy.