Well, time for a NERD RANT!

Remember when the heroes found the Jawa crawler? The blast marks were too precise for sand people? But then the heroes in civvies were able to waltz right through stormtrooper fusillades in the Death Star. Strange, right?

Except NOT!!!

First, uniforms help dehumanize enemies. It's psychologically easier to shoot Generic Enemy Soldier TK-421 than it is to shoot an obvious individual.

Second, remember, the goal was never to kill all the escapees. Obi-Wan died for nothing, because the Empire wanted the Millennium Falcon to escape with its tracking device that would lead them to the rebel base. The troopers must have been ordered to use suppressive fire to herd the heroes instead of just blasting them full of bolts.

IT WAS ALL PART OF THE PLAN!

[/rant]