WillCAD

The "ticketed passengers only" requirement was not originally meant to enhance security, since everyone who transits the checkpoint gets (in theory) the same level of scrutiny. Rather, it was meant to reduce the overall number of people who were screened on a daily basis, because the increased screening process post-9/11 took more time than the pre-9/11 process, and nobody wanted long lines at the c/p. I guess a few people were actually worried that large crowds at the c/p would present almost as tempting a target to terr'ists as the aircraft themselves.

As with so many things related to TSA, the common perception that the "ticketed passengers only" requirement somehow magically kept terr'ists out of the sterile area came about through complete and utter mindless ignorance. I think the public began to see "ticketed passengers only" as some sort of magical anti-terr'ist force field right around the same time that a few stowaways were discovered entering the sterile area on expired, lifted, or fake boarding passes, which prompted TSA to prevent stowaway entry by matching the BP to an ID.