I am thinking over my driving experiences, and I can't think of why or when I've had a cyclist be a few feet away from me and oriented in a way that put his light in my face. That would put him pretty much climbing my hood, about to be annihilated in a head-on. Look, the only time cycles and cars are a few feet apart, the car is passing the cyclist, or the car is stopped and the cyclist is crossing at the pedestrian cross walk. The driver isn't getting any face-on from the cycle's headlight. Turn it around, I am thinking about my riding experience, and similarly I can't think of when I have been a few feet from a car with my bike headlight pointed at his face. Even with the helmet light, when I have deliberately put the spot on a driver, I've been 40, 50, 60 feet away - approaching an intersection where the car is creeping out on the cross street, or approaching an intersection where the car is approaching from the on-coming direction.
There is only one time I've put my helmet spot right in a driver's face from just a few feet away. He had just swerved toward me from behind on a bridge, honking and accelerating away. Stupid prick. He didn't think about the traffic lights on the road after the bridge. I caught up with him as he sat at a red light, from a yard away, put my rated-1000-but-really-600-lumen helmet spot right in his night-adapted eyes as he ranted about me not having license plates, with his eyes closed, hands over his face. I imagine he was seeing spots after that. Gee, I feel so bad, I "blinded a driver".
I was driving around tonight doing Xmas shopping, and I saw a lot of cyclists. It was dark and raining, water streaming on my windshield, reflections on the slick black streets, stores lit up for shoppers, cars and bikes criss-crossing in the tail end of rush hour. The cyclists with a single weak light - like an AA-powered Planet Bike light - were hard to see, especially if they were wearing dark clothing. They were just dim little lights bobbing along amidst the glare from car headlights. The cyclists with bright lights on their bars - I'm guessing 300-500 lumen rechargeables - were more noticeable, but if their clothes weren't reflective, it was still easy to overlook them, as I was peering through my dripping windshield for cars and pedestrians. The riders with bright and blinking lights, or with bright lights on both bars and helmet, were pretty conspicuous. The blinking immediately communicated "bicycle". The dual bar and helmet lights somehow gave the rider a size, a stature, that communicated "person", and the helmet light also attracted attention by its waggling movement. In all cases, reflective clothing helped a lot, by outlining the rider's form and by moving as he pedaled. I was also reminded of how easy it is to be right hooked. Even if you do look over your right shoulder as you prepare to turn right, it is very easy to miss a cyclist approaching in the dark. His bar-mounted headlight is actually below the belt line of your car. I will be even more careful to play my helmet spot over the cars' right side mirrors or even their rear view mirrors.