The involvement of PI's in licensing of the security industry can be traced back to at least 1952. The PI industry was petitioning for licensing long before it became popular with the rest of the Security Industry.
The comment re the stuff of fantasy is misplaced. Investigators in private practice existed long before law enforcement investigators.
The quality of investigators I suggest is much the same as the rest of the industry. Many are extremely well qualified, experienced and professional.
Chris Brogan MA, LLM, LLB, BA, Fellow Of the Security Industry and 30+ years experience as an investigator in private practice.