Why do reversing trucks not beep anymore?

Here in NYC, a ton of vans and trucks still use the annoying beeping noise to indicate driving in reverse. The only time I've heard the white noise reverse sound is on construction sites where big industrial machines are either turning or reversing and must alert workers in the area. The sound is just as loud as a beep but quickly dissipates once you walk away from the immediate surrounding danger area (behind a truck/machine).

Compared to beeping, the newer white noise sound is easier to pick out both in volume and in directionality. And with an audio signal that's only heard where needed, that means a whole lot less noise in general. Yay! We need more of these everywhere.