On Sat, 13 Feb 2016 06:38:07 -0700, Gene Yuss wrote:

Brake lights should broadcast a wifi signal that flashes the
smartphone screens of the texting driver(s) behind you when
you apply the brakes. Or is there already an app for that?

How about coded beeps from the horn to warn drivers & pedestrians close by
who are NOT texting. I would not recommend this simply for applying the
brakes, and probably the beeps should be a bit muted. But it could give a
heads-up to those close at hand when:

1) The ABS is active. Usually, this means that the driver has allowed his
speed to exceed the safe limit to bring the car to stop without activating
the ABS. Possibly the car cannot stop to avoid hitting a pedestrian, and
the driver will not have time to think about sounding the horn.

2) Automatic redar-controlled braking is was actived. Usually, this means
that either the driver or a nearby pedestrian has erred in judgement.

3) The lane-keeping alarm was sounded within the car. Possibly the driver
is impaired by fatigue, texting, or intoxicants. Warn everyone nearby.