David Allegretti and his mate Sean conducted a little experiment, and they were shocked by the results. They bought a few hi-vis vests and then they put them to the tests. They used the vests to enter restricted areas, and they quickly discovered that no one questions people when they’re wearing one of these vests.
Considering they cost less than ten bucks each, this is a little worrying from a security angle.
In 2002, at the first St. Patrick's Day parade in NYC after September 11th, when everyone was still cagey after the atrocities, I was amazed at how easily I was permitted through security barriers without having to show I.D., just because I was wearing a fire department chaplain's uniform. Considering those uniforms run about $200 [back then, anyway] and can be purchased online, that seemed to be a considerable hole in the otherwise elaborate security screen.