Brinks security special treatment bad?

Today I saw a Brinks security officer walk into a bank with a pistol strapped to his side, and an empty bag in the other hand. He got no special looks from the people inside and never even got questioned from the clerk. He walked straight through their little half door and walked out a few moments later with a full bag and left. If a perp wanted to rob a bank wouldn't this be the easiest way to gain access to the vault/safe or wherever their money is held? Am I the only one that sees this as an issue?