Essentially, the High-Beam Assistant takes from the driver the burden to switch back and forth between high-beam and low-beam to accommodate oncoming traffic. A simple version of a high-beam assistant continues to use low-beam and high-beam and merely automates switching between them.
A more sophisticated version, sometimes called Adaptive High-Beam Assistant, leaves the high-beam on but cuts out oncoming traffic as it moves through the beam. This requires some intricate technology in the headlights to generate a moving shadow, e.g., an array of LEDs and adjustable lenses.
I was recently driving a base-model 5-series BMW as a rental, that was equipped with the simple high-beam assistant. It worked wonderfully and I was surprised to see it distinguish oncoming traffic from fixed lights and reflections (from signs, reflecting my own beam) without a single miss. I was also surprised by how much less stressful night-traveling was thanks to this relatively simple addition.
The simple High-Beam Assistant should come standard or as part of the Tech Package. The Adaptive High-Beam Assistant would probably warrant a paid option in its own right.
A 2013 BMW X3 offers a simple High-Beam Assistant for $1000 (which includes lane departure warning), so the estimate the price might be around $400 for the simple version.
Now standard on all cars that have Autopilot hardware.
From what I know of BWM uses the rearview mirror to control High beam. So the camera is mounted in the mirror. It is optional to look at road signs in some designs.I think. If it only did high beam control it should be well under $2000 since it typically ties into the existing car bus structure.
Already engineered by others, let's not forget. BMW has put a lot of effort (both time and money) into this feature. And although on my BMW I have it and it works wonderfully, this cannot be implemented easily. It's a lot of work and it requires a separate, high definition camera on which the car's software does image recognition several times a second. Incidentally, this same camera and same software that does the high beam assist also does the traffic sign and speed limit recognition in my BMW. No way we can have this for under $2000+
This is another simple (already engineered) feature that Tesla should include. You are building (have built) a techno-masterpiece. This kind of technology and many more similar innovations should be in your DNA, emoting from every creature comfort possible.