In the same way that ANH is a homage to john Ford, kurosawa, and old war films through a sci fi serial lens, AotC is an homage to mid century melodrama and B movies through a sci Fi lens. A 50s diner is there because everything about the movie is 1950s coded
I FUCKING HATE DEX'S DINER WHY IS THERE A RETRO 50'S STYLE DINER IN MY SPACE OPERA WHY DOES HE HAVE THAT AWFUL MUSTACHE WHY DOES HE KNOW ABOUT KAMINO AND CLONES WHY DOES HIS WAITRESS HAVE A BROOKLYN ACCENT THIS IS THE ONLY GODDAMN TIME THIS CULTURAL STYLE SHOWS UP IN STAR WARS