Ask HN: Some countries require a photo included in your CV. Why?

I'm from Germany and here we have a tradition of including our photo with our CV. Nobody knows why, but it's just "something you do." A CV without a picture is probably going to be thrown away.

German Wikipedia has this to say:

In keinem anderen Land wird jedoch das Bewerbungsfoto in einem Lebenslauf so hoch gewichtet wie in deutschsprachigen Ländern. Lebensläufe ohne Fotos landen nicht selten bei den Absagen.

Or a translation (mine):

In no other country outside of the German speaking ones is a photograph so important. CVs without pictures are usually rejected.

I haven't asked a Swiss or Austrian guy, but the Wikipedia entry leads me to believe photos are more or less required in those countries as well. I've also been told by a Spanish friend that it's normal to include in Spain as well. I'm sure there are other countries where it's required (in the sense that it's so normal) to include your picture in your CV.

My question is, why? I can only think of negative situations of including a picture where you're rejected due to your race or color, or that you just don't look "right" (ugly, queer, whatever) to the manager. On the other hand, I guess if you're an insanely good looking guy or girl then a manager might also give your CV more weight because they're attracted to you, which is also bad.

Also, what country are you from, and is it considered normal to include your picture as well?