Most home appliances have several options each of which depends upon the customers preference or pocketbook.
Refrigerators come with or without ice makers.
Stoves come with a choice of cook tops and features which promise to make meal preparation a snap. We are all impressed with the various options which are available in today's automobiles. However, there are certain things that are not optional. For example, when one is purchasing an automobile, the wheels, brakes and steering wheel are never listed as being optional. They are essential to a car being a car and performing the function of a car.