Nigeria, Oct. 10 -- Barely three minutes into its journey from Ilaro to Sango-Ota in Ogun State, a vehicle carrying fresh maize was stopped at a police checkpoint along the Ilaro-Papalanto road. It was in the first half of June, and the midday sun burnt the skin gently. The 2001 Sedan vehicle had no side mirrors, and the police officers, rifles slung over their shoulders, waved the driver aside. They exchanged a knowing smile. The driver knew the drill. Without argument, he slipped a folded N500 note into a waiting palm. The barrier was lifted, and the vehicle moved on toward Papalanto.

By the time the vehicle arrived in Sango-Ota, the driver had paid almost N4,000 in illegal fees and "tolls" at nearly a dozen checkpoints. From Ilaro thr...