With the proliferation of the theft of Airline Crew's Outfits over the past couple of months in the New York region, I feel it is an absolute must that EVERYBODY be screened at security. No if's ands or buts.
It seems that the TSA feels the same way, but there are a lot of "buts".......
Nearly every worker at almost every airport in the US is NOT subject to any screening at all. In fact, the only ones that are required to be screened at work are pilots and flight attendants.
Do you think it would be easier for a potential hijacker to pose as a pilot, bluff his way into the cockpit, start, push back, taxi and fly the aircraft into a building OR get an entry level job with a contract cleaning company/provisioner, bring a weapon to work in his lunch bag, place it under the lav trash bag and board the flight as a passenger later on, or have a partner do the same. The person boarding as a passenger can get every cavity searched by the TSA, and still have a weapon at his disposal.
The guy with the pilot uniform doesn't need a weapon, since, if he was able to get the airplane in the air, he ALREADY has control of it.