The Security Van Scam is well known but people still fall for it and simlar scams. Its got all the hallmarks of social engineering, including social complience, convincing and timing. From Schneier's great blog
on Thursday, about 9:30 a.m., a man dressed as an employee of the security company Brink's walked into a Wachovia branch in downtown Washington and walked out with more than $350,000.
The man had a badge and a gun holster on his belt, said Debbie Weierman, a spokeswoman for the FBI's Washington field office. He told officials at the bank, at 801 Pennsylvania Ave. NW, that he was filling in for the regular courier.
About 4 p.m., when the real guard showed up, a bank official told him that someone had picked up the cash, D.C. police said. The guard returned to his office and told a supervisor that he did not make the pickup at the bank. The supervisor called a Wachovia manager, who in turn notified authorities. Police were called nearly 11 hours after the heist.