The Nigerian police force has been voted one of the worst in the world and most of the reasons which is widely accepted by Nigerians are :
1: You do not dare argue wi5g a policeman with a gun... Suicide mission.
2: In other countries, when a policeman stops you in a traffic for default and you try to sip your hand in your pocket, you are shot, the police in Nigeria will smile instead because they know you have something to give to them... Bribery.
3: They arrive 20 minutes at a robbery scene after being notified, the robbers might have then escaped, they end up arresting innocent passersby if there is nothing left for them to do.
4: Bail in Nigeria is free, but they charge you ten thousand naira before they release you.
5: Police is your friend, but they are actually your enemies, there is no much difference between them and gunmen.