It was an inside job. Obi Wan paid the Sand People to kill the Jawas and Luke's auncle and aunt so that Luke will follow him to become a Jedi. Remember, the Sand People thinks Obi Wan is a mythical monster/god.
> but but Obi Wan is a good guy!
No! Obi Wan has shown in the Prequels to be a sly manipulative guy. He justifies everything by "looking at it from a certain point of view". He lied to Luke about Vader too. He's also not above mind controlling " weak minded" muggles. All the pieces line up. Wake up banthaples!
They're looking at random pot shots on the side of a gigantic sand crawler. Were those shots even precise? It seemed like they hit armor and did fuck all for the most part until one dude randomly got lucky and hit the gas tank or something.