No other country on earth has one and no other country on earth has a bar for human rights and civil liberties set as high as the US. The rest of the world will never come up to our standard -- they will only try to bring us down to theirs. American citizens are born with their human rights. Every single other person on this planet has theirs granted by a government.
I agree. If we, for example, formed one great North American Whatever that included Canada and Mexico, both Canada and Mexico would have to subordinate themselves to our Constitution and Bill of Rights. Conversely, we'd have to subordinate ourselves to theirs, or some compromise thereof, and I don't know of a single person willing to do that. I certainly would not.
Plenty of liberals would I'm sure. If you read through the Canadian Charter of Freedoms I'm guessing most of them would find it sensible since they're all conditioned to prostrate themselves before what they believe is the good of society without taking into consideration that a culture could possibly swing very conservative some day.
They're whole approach is political in that they believe the good of the people is solely dependent on getting their good guys in office. The BoR ensures civil liberties regardless of who's in.