Used to be, the DOT had national standards for specifications on car headlights that included brightness. For some years now, there doesn't seem to be any standard in how bright headlights may be and they get brighter and brighter with every passing year.
I can't speak for what's going on in other parts of the country, but young pukes around here like to install extra-bright lamp bulbs in their little Japanese cars and blind everyone else. Like with the blue lights, for example. I'm not sure why they do this; a form of aggression I guess, like they have brighter lights that you do, hahaha. Having the brightest light is like having the fastest car; it's a form of oneupsmanship. Or they get a feeling of power from being able to blind other motorists.
There's no getting around it, but for some people their eyes become more sensitive to light as they age. However; I've never liked having bright lights pointed in my eyes at any age.
Remember the days when the police would pull you over for headlight offenses? These days, there aren't enough of them around to waste time on such trivial matters. Also, as bright as headlights have gotten on newer cars, how would they even tell if someone was driving around with their high beams on?
Then there's the deal with fog lights. Lots of people who live in the city and the 'burbs feel compelled to drive around with fog lights on in addition to headlights, in any weather. Just because. I know extra illumination is nice to be able to see, but it comes at the expense of every other driver that is forced to deal with overly-bright lights.
I guess some of this comes as a consequence of of the lack of civility and manners that keeps creeping insideously into our society. In times past, motorists might've had some consideration for other drivers on the road. Now, it's "I've got mine and screw you, Jack."