Color schemes?
Some years ago I was at a red light and heard all sorts of fire trucks sirens. Couldn't see where it was coming from and then, I could finally see the lights, on a yellow truck. Yellow? Fire trucks don't come in yellow, they're always Fire Engine Red. (Even if there are 40 shades of that.)
Just happened to be one of the first trucks in one of the first years they debuted the chartreuse aka "high visibility" color on fire trucks, and I was in a town that was testing it out. They had a lot of trouble with that, because everyone would look right at the trucks and ignore them, since fire trucks weren't yellow.
But of all the assorted emergency response vehicles I've seen, I think the Brits still do the best job with those huge checkboard patterns on their cars. Somehow, those always stand out.
There's just something, well, flat out wrong about a vehicle being used as an ambulance but sold with a "Police Interceptor" (PI) package on it. As if ambulances need to outrun police cars and chase them down?
As with NYS's continual changes in licenses plates, there are always all sorts of "scientific reasons" why a change has to reverse whatever the last change was. Usually, because someone's nephew needed a job.(G)