In Europe lights have much better quality optics, that are less blinding to oncoming drivers at the same light output. For the most part, these are not US legal, and the even same European car models when sold in the USA have much worse lights that dangerously blind oncoming drivers.
I have always (illegally) retrofitted my vehicles with European versions of the headlights, and I can see much better, and blind other drivers less. It is absolutely insane that having safe headlights is illegal in the USA.
In general car headlights in the USA have to be DOT compliant, meeting a strict set of regulations... and the new and innovative or unusual designs on high end foreign cars can fall outside those for one reason or another.
For example, back in the 70s and 80s the only compliant lights were extremely dim disposable sealed beam light bulbs with an integrated lens and reflector. European cars had high end optics with large glass lenses and mirrors that used a replaceable H4 style bulb, but the American versions had to swap that entire system for something with a low quality disposable bulb. Car enthusiasts would often buy the better lights from overseas and swap them in. While technically illegal, not cop is going to ticket you for not blinding them enough. Nowadays at least American cars do have replaceable lights and not sealed beams.
A more modern example, is that European cars have long used dynamic/adaptive lights that actively detect and block the light going towards oncoming vehicles by dynamically reshaping the beam- a much more effective system than just having low beams that point lower. They also have steerable headlights that point away from oncoming traffic into turns, and automatically point the lights down if the vehicle suspension squats in the rear from a heavy load or bump. While they've long been legal and widely used in Europe, they are now legal in the USA as of 2 years ago- for example you can now order a new VW with "Dynamic Light Assist" option, which actively reshapes the beam.... but this is so recently legal almost no vehicles on the road have it yet.
A lesser known trick is you can flash your highbeams before cresting a hill or going around a blind turn to warn drivers on the other side. I rarely encounter other drivers who do this, but when I do it almost always works.
It's hard to tell really if always-on high beams are now common or if SUVs + superbright beams makes it seem that way, especially given there are a lot of hills that can make any car's high beams seem on.
Still, I feel like "civility" here is breaking down and not turning off high beams may be a part of it (though I'm aware that feeling may be coloring my perceptions).
I think it's a little bit of both. I believe the latter started the trend, and that confusion has led other people to just say screw it.
It 100% is when I was learning to drive in the 90's. Growing up I remember driving up the desolate back-roads of upstate NY on our way to VT and my father loosing his shit when some moron kept their high beams on. It was rare.
I bet a lot of it has to do with modern car automation where auto dimming and other features are expected by newer drivers to just work and they blissfully drive around expecting the car to do everything for them. Laziness rendered by convenience.
Take the hint and complain LOUDLY at your dealer until they do something about it.
https://static.nhtsa.gov/odi/rcl/2022/RCLRPT-22V903-6333.PDF