But, DRL only make sense if they are mandatory (and, preferably, automatic); otherwise, if only most drivers use them, those who don't become kind of invisible (and so dangerous for themselves and others).

If DRL are hurting your eyes in broad daylight, then there's something clearly wrong with them. As I said, we use regular low beams here, and they seem (to me) to be just brigh enough to make car visible sooner, and not bright enough to be annoying or distracting.

My estimate is that I notice the incomming car with low beems on at 1.5 to 3 times greater distance than the one without, depending on direction and quality of ambient light, car colour, background etc. The similar is true for that Porshe comming from behind at 200+ km/h on highway.

BTW, headlight alignment check (together with brakes, steering and exhaust) is a part of mandatory annual test every car must pass here in order to renew its 'roadworthiness' license.