This whole horn toot versus blast thing.
It may depend on the horns or circuit in the vehicle if the horns can even be controlled to give out a low volume "beep".
My wife's car with American Ford horns, pretty much hit full volume even with an attempted light rap of the horn switch. My Mazda with a set of Hella horns puts out a very low "beep" with a light rap of the horn switch, while the volume increases substantially if I lay on those Hellas. I'm going to say it's the horn switch control of my car that makes this control easier. My car's horn switch, under the airbag, is very light and responsive. My wife's car, not nearly as light and responsive.
I figure that anyone that has a car with a light and responsive horn switch and electrical circuit can finesse the horn in polite little "hellos" to huge "eff offs" rather easily.