In-setting reason -- hyperspace is full of junk and shadows, and part of the challenge of making a fast run is making the shortest run in actual distance while avoiding it all.
Real reason -- George Lucas couldn't be arsed to do his **** research.
Like most writers, which is why cars explode when they hit, or have a strange tendency to jump into the air in a crash with another car.
Or just basic physics for most any story. Like fist fights where the worst that seems to happen is a slight limp or a bloody lip after a 10 minute brawl. Or people falling 40 feet and just walking away.
Not claiming Lucas is at all rare in this regard... I still don't care for it.
If I were going to make a movie with gunfights, for example, the first thing I'd do is start interviewing people who'd actually trained for and been in gunfights, about what they're really like, what trained combatants actually do, etc.
I'd look at how cars actually react to collisions if there was a car wreck in the movie. .
Edited by MaxKilljoy