Canada

Headlights are regulated and tested by brightness, not power consumption, so it's already what you suggest. The problem is brightness is tested using a few very standardized tests.

LED arrays make it easier to engineer uneven brightness throughout the area of the light beam, e.g., dimmer in the middle than the outside, dimmer on the left sides, etc. This means manufacturers can make headlights that are overall brighter than allowed but can still pass tests as the region tested by regulators is designed to be dimmer, so the test results are acceptable.

I used to accept that explanation, but even "perfectly adjusted" headlights become super blinding when an oncoming car approaches at even a slight upward hill, which is super noticeable now that most new cars seem to come with LED headlights as standard.

The factory ones are blinding now. This isn't a misalignment issue anymore. At one time you could say that and have a good chance of being right.

I would say it is kinda both. Either people have misalingned lights, they are too fucking bright or they do both at the same time.

I passed LED cars that were great in terms of brightness and those that were not. Same with regular lights.

There is also good number of people who use these lower fog lights every time they drive.