Bingowings said:
If Tatooine is as out of the way as Luke complains it is Tarkin may actually be more familiar with the space port name than the planet name.
Before the first Gulf War Baghdad (through it's associations with Scherazade) was culturally more recognisable than Iraq to the clueless masses.
That's a whole new piece of story you'd have to tell onscreen before that explanation makes any sense.