You can see very clearly where the higher intensity area of the beam cuts off, and he probably doesn't get flashed by oncoming cars.

If only there were some sort of signal other drivers could make to indicate my beams were too high!

Xenon lights actually have a lower cutoff on the drivers side because the designers were aware of onlooking from the opposite direction (and on the left of the car in the U.S.)

They are bothersome, you see this comment saying they are bothersome.

Yes, but I don't see anyone flashing at me to turn them down...

What possible good would that do? You can't make them un-xenon. If I flash my lights or not, you'll still just keep toodling along blinding everybody in the oncoming lane.

If I see ultra-bright lights, I assume the other driver has the high beams on and flash them. If you can tell that they have misconfigured low beams, you wouldn't do that, but I'm going by my experience and assume that at least a few drivers would act the same way.

You know what happens when you flash a teenager who has super deluxe Xenon lights? You get flashed back, double blinded.

"Turn them down." What do you have a rheostat on your headlamps? Keep them "down."