Your major appliances serve you for many years because of Porcelain Enamel. The best ranges and ovens are of Porcelain Enamel. Quality washers and dryers have Porcelain Enamel tops and baskets. This finish will not rust or scratch like plain painted steel.
Porcelain Enamel has no pores or scratches to provide bacteria with a place to grow. And it will wipe clean in seconds. It will not scorch, burn or discolor in a sustained high-temperature environment.
Your water heater is lined with Porcelain Enamel, you'll often hear it referred to as "glass-lined."
Paints, plastics and stainless steel cannot fulfill all of these needs. Porcelain Enamel is simply the best finish available for your appliances.