You don’t even need to get near security. You can walk into any major airport in North America with numerous pieces of luggage and line up with hundreds of other people at the intitial check-in counter for your airline. No security check and usually no visible sign of any security officials. Just airline ticketing personnel and some porters. I’ve been in line at the Toronto airport when there would easily be 500 people lined up in an area 100 ft x 100 ft. It’s even worse lining up outside a major sporting event. Just think what a car bomb could do in front of the gates at the Meadowlands on game-day for the Giants.
The last report I read said it happened outside the exit from the baggage claim, which was full of taxi drivers, porters and family members waiting for passengers to come out with their luggage. Anywhere you create a queue you’re going to have a vulnerable target and there’s no way to entirely prevent that scenario. In the early years of the second Iraq war, suicide bombers frequently attacked Iraqis who were lined up outside the Green Zone looking for work. If you did an initial screening outside the aiport doors, then the next attack will take place at that point. The terrorists will always seek convenient targets.