Dishwashers will reduce the spread of germs. A dishwasher is washing the dishes in temperatures of 50-75°C, a far higher temperature than hands can tolerate. Dishwasher detergent is far stronger than washing up liquid and contains ingredients which ensure food soils are broken down and washed away during the washing cycle. Combined with the very hot water and the mechanical action of the dishwasher, a far higher standard of cleanliness is achieved than could be by handwashing. As a result, harmful bacteria are destroyed that might otherwise remain unseen on your dishes
A used, damp tea towel can harbour up to 30,000,000,000,000 (30 trillion) colonies of bacteria - such is the rate at which bacteria multiply. Dishwashers dry your dishes for you, so you don’t need to use a tea towel.