Watch this interesting segment from VICE News about a man named Frank Argenbright who headed Argenbright Security and came under fire months after 9/11 for allowing 9/11 hijackers through security at Dulles Airport.
The TSA is such a normal part of flying these days that it's often easy to forget that security at airports was handled by private security firms prior to the 9/11 terrorist attacks. According to this video, Argenbright and his security firm were blamed heavily by the American government which led Frank to get out of the airport security business.