I would agree...more to the story. If you land in Frankfurt, and stay within the international flights area, you don’t meet customs or border patrol folks. They must have exited that area for some reason.
True, but Frankfurt is in Germany and the were arrested in Zurich
In July, my travel through Paris for a transfer required that I go through customs again just for a transfer. I think it was because my connection flight was within the EU. The same is true when I transfer in JFK to a connecting USA flight.
But Switzerland is not in the EU.