I hear it happens all the time. The police work for the government, the government is controlled by the wealthy, and the wealthy do not like the criminal class. They view them as a threat to their existence. Therefore, the police spend their time locking up criminals or just killing them. The police get a small bonus for every unregistered person they lock up or kill.
Police also like to bust drug dealers because they have a lot of money.
From what I hear, the police won't even touch these drug dealers. They'll just take all the money and go on their way. Kind of like paying taxes. The police will come back and bust the same dealer every couple weeks. Being a big time drug dealer is a respected profession because it generates money for the police.