Originally Posted by
jkhuggins
Wild, unsubstantiated speculation follows.
1) The "pre-security security checker" might not be affiliated in any way with TSA. If, as suggested above, they're just trying to divert people who don't have boarding passes and IDs aside until they get those documents, in order to improve the overall throughput of the line, then showing them your ID doesn't actually satisfy the TSA's desire to verify your identity.
I believe this is accurate based on recent experience at IAD. They have made numerous changes lately and I would guess that it could be confusing for people who have never been there before or those people who HAVE been there and now everything has been changed. Making sure people are directed to the correct area is probably a good thing. That being said, I have seen on almost every occasion people who were clearly not flying that day (just waving goodbye before the last security area) going downstairs past these people asking for BPs.