I can't tell you about what other countries do...but dipping the United States Flag to anything or anyone is illegal by our Federal Code. In particular:
United States Code Title 36, Chapter 10 §176.
Respect for flag
No disrespect should be shown to the flag of the United States of America; the flag should not be dipped to any person or thing. Regimental colors, State flags, and organization or institutional flags are to be dipped as a mark of honor.
So, the question is...why do OTHER countries allow their flags to be dipped?
It is true that we don't dip our flag at the saluting point and the reason is that it's against U.S. law. The relevant paragraphs are (c), (e), and (g). These laws, IIRC, have their roots in the American Revolution and the prinicple that, as a free people, we will be subservient to no one.
I'm fairly certain, however, that we are not alone in this. I think the old Soviet Union and The Peoples Republic of China do not dip their flags, either, but I could be wrong about that.
i've 'dipped my flag' a few times and man it brought me nothin' but trouble! /forums/images/icons/laugh.gif /forums/images/icons/blush.gif it's even worse when i wear my stars and stripes boxers /forums/images/icons/tongue.gif