h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

In Canada, drivers are strongly encouraged to drive with their headlights on during the daytime, as studies have demonstrated that other drivers are far more likely to see you coming and consequently there will be fewer accidents.

Whilst driving in Switzerland in 1994, in the daytime, with our car headlights on, we found that the driver of just about every second oncoming car would flash their car headlights wildly on and off as they passed us. Now in Canada, the flashing of the headlights by an approaching driver means one of two things: 1.) WARNING! There is a speedtrap ahead - slow down! or 2.) Your high beams are on and they're blinding me you moron! As we were driving in the daytime and didn't have the high beams on, we knew it couldn't be that, so for quite some time, we were concerned that somehow we'd misread the speed limit sign, so we kept slowing down, but everyone was passing us. We eventually learned that a very normal, highly encouraged, safety conscious act was a horrible faux-pas in Switzerland.

Having driven around Switzerland for ten years, I must say I've never encountered the behaviour you describe. A typical Swiss reaction to seeing an on-coming motorist with his headlights on would be to assume that there was some local by-law, which he/she wasn't aware of, requiring headlights to be on at all times, and therefore to turn his/her headlights on as well.
One interesting thing about Swiss driving etiquette is that the car number plate immediately informs everyone which part of Switzerland you come from. Beware therefore of any car with the number plate prefix AG. The people from this part of Central Switzerland are notorious for being the worst drivers in Switzerland - a reputation which is my experience entirely justified. Also stay out of the way of any car with the prefix TI. It belongs to someone from the Italian-speaking part of Switzerland. It must be something in the genes, but these people, the Ticenese, drive as crazily as their counterparts over the border.
The number one object of fear and derision on Swiss roads is however the Dutch Caravan Driver. Easily identifiable by their yellow number plates, these vehicles plague Swiss roads in the Summer and invariably cause traffic mayhem as their drivers freak out and forget all they ever (allegedly) knew about driving at the first sight of a mountain.