Airconditioner Servicing

I have two vehicles. When I purchased the vehicles I was told that the vehicles must be serviced timeously as recommended by the manufacturer of the vehicle. Insurance companies expects the owner of a vehicle to be keep the insured vehicle in a roadworthy status at all times. Please tell me why the airconditioner is excluded from all services and why the vehicles owner is not informed to service the airconditioner of the vehicle yearly? I have owned Toyota, Volkswagen, Opel, Mazda and a Ford. Not once did a mechanic or service agent or salesman inform me that airconditioner service must be done yearly. There is massive costs involved when the unserviced airconditioner breaks down. Surely clients must be informed of all services required for their vehicle. Including Airconditioner servicing. P.C.Greyling