Well, I use "US" as much as I do "Bush" McGrath. And the reason is because it often goes way beyond the president, cabinets, legislative bodies, etc. I agree though, that sometimes it is very important to make that distinction. In this case, when I say "the UK" I'm including more than just Tony Blair, but I'm not including the majority of citizens, in keeping with the way Blissfully Ignorant put it in his/her post:

Britain being the first in line to lick the behind of the president. Perhaps we're sore about not having an empire any more, so we grasp onto the shoulders of whoever's in charge in the U-S-of-A in the hope of getting piggybacked to glory as the new American empire is conquered.