Why did the stormtroopers kill the jawas and then make it look like the sand people did it?
Huh? Luke assumed sandpeople did it. Then Obi-Wan said that sandpeople walk in single file to cover their numbers, and that the track in the sand are shown side by side, aka Stormtroopers.* The Stormtroopers didn’t even try to make it seem as if sandpeople did it. Luke only assumed that since it’s implied Jawa’s and sandpeople don’t get along.
*I probably am not relaying the words accurately, but regardless, Obi-Wan pointed out how sandpeople walk differently compared to Stormtroopers.