Witness identification and other problems in investigations make it hard to solve crimes much of the time. So the police and courts will do a hoax crime so that they can catch the criminal and punish him. This way they don’t risk punishing an innocent person.
The hoax crimes are the trials of the century. They are really cop shows like on TV or in detective fiction. Sherlock Holmes was invented and promoted for the same reason. They are to send a message that you can be caught. They are like the message that God is watching.
Cop hoaxes are an admission that the cops and courts are unable to control real crime except by deception.
The more spectacular the crime, the more it is a crime of the century or trial of the century, the more it is a hoax.
Ruby Ridge, Waco, OK City, OJ Simpson, 911 were all hoaxes.
This is draft and preliminary. The above is hypotheses and speculation. Comments and corrections welcome. Please restate as questions. All other disclaimers apply.