Because only 15 of the 19 hijackers on 9/11 came from the Wahhabi kingdom.
Via IPT:
Saudi Arabia, the nation which produced 15 of the 19 hijackers in the 9/11 attacks, is about to become one of a handful of countries whose travelers can bypass normal passport controls at major U.S. airports. Sources tell the Investigative Project on Terrorism (IPT) that this will mark the first time that the Saudi government will have a direct role in vetting who is eligible for getting fast-tracked for entry into the United States.
An agreement to accept Saudi Arabian applicants into the Global Entry trusted traveler program drew little notice when it was announced in January. Now, some officials question why the country merits such a benefit – which is similar to a theme park “fast pass” to avoid long lines – when other allies like Germany and France are not yet included. A program for Israeli travelers was reached last May but has not been implemented.
Travelers approved for the program can skip the normal Customs and Border Protection (CBP) lines starting next year and enter the country after providing their passports and fingerprints at a kiosk. Only Canada, Mexico, South Korea and the Netherlands currently enjoy the benefit, although pilot programs could expand it to a handful of others.