I ride a bicycle, and I deliberately mount the rear light directly at the eye level of typical sedans and SUVs. It's not connected to the brakes, but I find that having the light pulse is enough.
I've got the rear flasher on my road bike tucked as high under the seat as it can get, but even with a large frame bike and relaxed commuting (non-aero) posture I'm shorter than the hood lots of full-size SUVs and pickups, much less the seat.
I agree with the other commenter that a 360 cam on top of the helmet has been the most important thing for deterring tailgating and road rage. I've added reflective tape on the frame, the blinking blinking lights under the seat, a headlight on the handlebars and a headlamp with front white and rear red light, and my backpack has a nearly fluorescent neon green cover. Those all help reduce the "Oops, didn't see you there while looking at my phone" close calls, but do nothing to reduce intentional harassment - that's the function of the camera.
Sorry if I was unclear. I have two rear lights. The first one is mounted on the seat post near the eye level of sedans. The second one is mounted at the bottom of the helmet near the eye level of large SUVs.
If you have a hub generator system, they sell rear lights with controllers which detect changes in the frequency of the wheel rotation and start pulsing when you decelerate.
Yeah, I have the Busch & Müller Toplight [1]. "The Toplight Line Brake Plus senses when the bike slows under braking and glows brighter. It does this by monitoring the AC frequency from the hub. During braking, the AC frequency slows quickly, and then makes the LEDs pulse or flicker, hopefully getting the attention of that fool in the jacked up SUV behind you."
That would be more difficult, expensive, and unreliable. The light is powered by the rotation of the wheel so it already has a reliable braking signal.
How is that difficult, expensive, or unreliable? What could be simpler than a switch that closes when a lever is closed, and turns on a light?
That sounds much simpler, cheaper, and reliable than "detect changes in the frequency of the wheel rotation".
Also, it works like a car's brake lights, which drivers are accustomed to, rather than "start pulsing when you decelerate", which is when you stop pedaling (unless going downhill).
The light is already by necessity hooked up to the wheel for power and adding a switch and wires to the brakes adds another point of failure making the system less reliable, makes installation more difficult because you have to wire up to the hub generator and the brakes, and more expensive because more components.
