Wars, floods, droughts, etc. also occur continuously. Unfortunately, they never published or broadcast the prediction, so there is no evidence. People have an amazing capacity for forgetting the wrong ones. Another feat of clairvoyance is finding missing persons or objects, solving criminal cases and the like. No case has ever been solved in this manner.
Investigators enlist the help of psychics usually as a last resort.
It is usually done to persuade the public that they are doing something when they have run out of clues. It is also done to scare a suspect into giving himself up, since criminals are often superstitious. This does not mean that law enforcement personnel are stupid or incompetent, but just that they have limited time and manpower to spend on any individual case. A man in England solved dozens of cases for Scotland Yard by simply reading accounts of the crimes in newspapers. He had no psychic powers, just better powers of deduction.