I think it reflects poorly on Luke's character that he could simply see the bodies of the two people who have raised him from birth brutally murdered and not even an attempt at burial
We have no idea from the film whether Luke buried his aunt and uncle or not. The scene shifts to the Death Star right after Luke finds their bodies in one of the most dramatic transitions in the film. We can only speculate that it probably would have been unsafe to hang around too long at the Lars residence. Luke was lucky not to have gotten picked off or arrested just coming back to make sure they were OK.