Final answer:
Restaurants avoid using dish towels to dry dishes due to potential contamination; they prefer sanitizing dishes using high-temperature dishwashers or allowing them to air dry. Detergents are necessary to remove the greasy film that water alone cannot clean.
Step-by-step explanation:
In a restaurant, health regulations often require that dishes be sanitized in a way that removes not just visible dirt and food residue, but also bacteria and other pathogens. Using a dish towel to dry dishes can introduce contaminants, as the towel may not be completely clean or sanitary. Instead, restaurants typically use a dishwasher that reaches high temperatures, which sanitizes the dishes, or they allow dishes to air dry, which eliminates the potential for contamination that a dish towel might cause. Moreover, hand dishwashing detergents and the dishwasher's high water flow help remove the greasy film that water alone cannot, as seen in the scenario where only water was used to rinse a salad bowl resulting in an oily film. Underlying this issue is the fact that water and oil do not mix, and the use of a proper detergent is required to break down grease and allow it to be rinsed away.