Symbolism, Imagery, Allegory
It's possible to read the Pardoner's Tale as an allegory in which the characters and events represent abstract concepts rather than "real" people or situations. The presence of the mysterious stranger named Death more or less invites this interpretation. In an allegorical reading, the Three Rioters represent greed (or possibly, all sin), and their death and the events surrounding it are an allegory for the journey of the sinful soul to damnation.
The Old Man they meet along the way, who counsels them to follow a version of the golden rule, might even represent Jesus or God's revelation, telling mankind how he should act to deserve salvation. The Rioters' failure to listen to his advice represents the turning-away of the sinner from God's Revelation; the Old Man's direction of them to the eight bushels of gold when they ask for the location of Death is a not-so-subtle commentary on how the desire for material goods leads to damnation.
And of course, the Rioters' decision to murder one another to acquire these goods represents that damnation, since by that point they've cast off all other considerations, including their plan to defeat Death, to keep the gold. Since the rioters want the gold for the life of luxury it'll enable them to lead, it's likely that the gold also represents this sinful lifestyle. In short, the Pardoner's Tale is the allegory of how the sinful soul ignores God's revelation and rejects the opportunity for eternal life in favor of a mortal life centered on pleasure and material things. You don't really need an X-Box and a PS4.