The senselessness of the crime points to the lack of moral development in Perry and Burkett, as well as poverty. The stolen car is shown later has having rotted in a lot, a tree root growing up into it.
Early in the film, a Conroe (near Houston) sheriff's deputy explains the evidence against Perry and Burkett, and his voice and manner of speech sounds just like mine in some of my own videos. This was bizarre. I thought I was listening to myself (and not playing piano).