Except with respect to the dental plan organization activities of a duly organized and authorized insurer or medical or dental service corporation, which activities are authorized and regulated pursuant to this chapter, this chapter shall not apply to a person engaged as indemnitor or contractor in the business of life insurance, health insurance or of annuity, nor shall it apply to a medical service corporation or dental service corporation. This chapter shall not apply to the dental plan activities of a duly authorized health service corporation.