Never thought having a reflective vest with security on it would be useful but I can see why. In the right situation of course. The comment section has a link to Whiskey being better, good, I like Whiskey myself.
I do keep a reflective green vest and white hard hat around. Gets me to places I might not normally be allowed to be in. Last year during windstorms when limbs and trees were falling I walked right up to our local fire chief to ask some storm time estimates for power restoration. We talked for a while and shortly after that a National Grid guy walked up to me directly and asked my assessment. Told him that we needed to get this street open and power on soonest. Ok he said and left. Chief was laughing his ass off, but five minutes later a cutting crew showed up and we had power within the hour . . .