Jar-Jar should've strayed into traffic-traffic. :P
Oh.. and Sandtroopers killed Jawas in Episode IV.
In response to your wondering why/when they'd kill them.
I'm hardly an expert on Star Wars, but I think it had to do with the Troopers looking for R2D2 and C3PO.
I THINK the killers were troopers, not Sand-People, anyways... <shrug>.