In the US maximum headlight brightness is regulated, but the rules and tests are written extremly poorly. The test is in a specific place at a specific angle,

In the US maximum headlight brightness is regulated, but the rules and tests are written extremly poorly. The test is in a specific place at a specific angle, so there are a ton of headlights that can pass the test, but are far brighter everywhere else. Obeying the letter of the law while flaunting the spirit. To make matters worse, due to the way the rules are written advanced systems that dim LED headlights specifically in the path of oncoming cars are not legal in the US. It's becoming common on high end European cars to not just auto dim but isolate oncoming vehicles from illumination while maintaining brightness elsewhere. The key to good regulation here is to write rules about how much light can be experienced by oncoming vehicles of various height and driver positions and let engineers figure out how to meet it.