HiViz vests save you from spontaneous combustion, earthquakes, attacks from crocodiles and being bitten by snakes, etc. - They are 100% effective! I've also not been run over by my own aircraft. Buy they are sod all of use in stopping you from being run over by vehicles on the apron. I've lost count of the times I've nearly been taken out. But I always wear one and insist my crew do the same. And if I do get run over, I'll sue the a**e of the airport where it happened. If the
wits want me to wear one, I'll do so. But I'm under no illusion that they do nothing for safety: the only thing they do is tick a box for the mentally retarded half-wits who think they improve safety at these places.
The same sort of thinking happens with all "safety" things at airports. Signs that say things like "This airbridge may only be operated by trained personnel in accordance with procedures", warning sirens and lights that go on for tens minutes, bright flashing beacons on every bit of equipment - buggering up your night vision, not reporting braking action etc. All of this ticks boxes but does nothing to enhance safety for anyone.