Is this still a big problem? While I would have agreed with you, say, back in the 2000s when the whole "import tuner" craze was in full swing, I don't think this is popular anymore. The car mod scene seems to be close to extinct now, with whats left being a lot less crazy than those in the past.
Especially true for midwest drives across long stretches at night where the brightness is much more annoying than in the middle of a city.
If the truck is lifted, the brightest points of the light can hit you from further away, worsening the problem.
It is also bad when someone is behind you with this setup, especially lifted trucks. Some cars have a rear mirror that can dim them to tolerable levels, but not the side mirrors. So you'll get flashes from them as you drive unless you lean forward or angle the mirrors away.
The US National Highway Transportation Safety Administration actually has a suggestion for eliminating the glare and reducing blindspots [1]
https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/blindzonegla...
What is worse about the LEDs is that they are sold as "compatible" to various vehicles, when that means they will work mechanically/electrically, but not optically (some actually try to put LEDs in the same spot as the filament). All of the units I've seen cause the car headlamp to put out light at higher angles than a halogen bulb will, causing more glare for opposing traffic.
No. Retrofitting Xenon bulbs is an expensive pain in the ass compared to dropping in some LED replacement bulbs for a marginal increase in light and little to no increase in glare or change in beam pattern because they're made to be geometrically equivalent to the halogen bulbs they replace (which they kind of need to be in order to work adequately in all possible applications for whatever bulb they replace)
At the very high end you can get stupid bright LEDs but pretty much nobody does that because they are expensive.
Most of the glare you see is from OEM headlight assemblies (regardless of the type of bulb installed) that were simply not designed with not blinding other people as more than a "check the compliance box so we can get back to optimizing for every other metric" sized priority.
In other EU countries they were however allowed up to a certain date (in Italy they are accepted only for vehicles built before 1993, and in the same date France made them not mandatory).
The yellow is not "a" yellow it is a very specific one, called "Selective Yellow":
Apparently it was to reduce dazzle and glare: https://en.wikipedia.org/wiki/Selective_yellow