You pay a membership fee for the CMPA which varies depending upon your area of work.    So you're correct in the sense that it's like a mutual company.    But that fee covers more than just insurance - it's a membership and with this comes acceptable practice guidelines and legal advice and defence (assuming acceptable practices were followed)  in the case of any suit.       And the fees of $100K per year are for surgical obstetrics, specifically in Ontario (the highest fee in the country).     So this fee isn't really applicable to this article since that type of practice is carried out in a hospital.     Typical GP or family doctor membership fees are up to $17K/year (the highest fee, again for Ontario, in the case of a general practitioner who also does anaesthesia, some surgery, and shifts in a hospital emergency.   

By way of comparison, a taxi driver in Toronto pays about the same for commercial driving insurance.