Why does a dish washing machine drain through the sink?

Dish washers usually drain through the sink because of simple logistics associated with their installation. The appliance is located near the sink in the kitchen because this is the center for cleaning and restoring to use our dishes. The dish washer doesn't use tons of water like a clothes washer, and if it is hooked up to drain through the sink (frequently through a port in a disposal), a separate drain line doesn't have to be run for it. It simply dumps the gray water out into the sink effluent line and it's all good.