Why was a careless driving ticket issued in Colorado for an accident that damaged my vehicle when I lost control after encountering black ice but no one else was involved or injured?

Because careless driving is a catch all (traffic violation) term that produces revenue for the state. It is your falult for not preparing for all possible events thrown at you while driving your vehicle.

I found this definition of careless driving: "Any person who drives any motor vehicle, bicycle, or motorized bicycle in a careless and imprudent manner, without due regard for the width, grade, curves, corners, traffic, and use of the streets and highways and all other attendant circumstances, is guilty of careless driving."