In fact, a fifteen-year-old boy had been arrested because he had stolen a piar of flip-flops which happened to belong to a policeman. The cop's first reaction was to beat the boy up. The boy's mother reported the policeman for brutality. That angered fellow cops, who arrested the boy. Now he was facing five years in prison. Meanwhile, people accused of stealing tens of millions of dollars where bribing judges and getting off scot-free. At worst, the biggest criminals were sentenced to just a year or two. Flip-flops quickly came to symbolized Indonesians' disgust with the arrogance of the law.
As long as Indonesians believe the police and the courts are rotten to the core - 'Report the theft of a chicken and lose your buffalot,' the Javanese saying goes - mob justice will continue to rule.