Pard'n me, and since when the Kalidor Crescent is Alderaanian?
Maybe Leia would've to actually fly a starfighter in order to get one?
So why Chewie didn't get one? (in the movie, he actually gets it in the novelization!) The official story behind this was that "Wookies are too proud to wear awards" or something like that. But hey, it's Lucas' Star Wars, remember? It had to be changed!
The fact that Chewbacca apparently does not receive a medal in the concluding ceremony in A New Hope bothered many fans. This was corrected outside regular Star Wars continuity, after a fashion in 1997, when Chewbacca won the Lifetime Achievement Award at the MTV Movie Awards. Chewbacca, played by Peter Mayhew, appeared on stage to a standing ovation and was given a medal from Carrie Fisher. It should be noted that in the novelization of A New Hope (ghostwritten by Alan Dean Foster, credited to George Lucas), Leia did give Chewbacca a medal, but she had to strain to do so.
http://en.wikipedia.org/wiki/Chewbacca
Try to google for the clip from that ceremony.
Now, I've got an even better question: why we never saw Wedge to get a medal? Or Lando? Or the other pilot surviving the Death Star attack run?