Stainless steel is not inherently sterile but it can be made sterile and its lack of corrosion provides no hidden cavities that might harbor germs. A stainless steel surface can be made relatively flat and it will remain that way indefinitely. In contrast, a rusting steel surface has a complicated surface that is constantly changing. That surface is harder to keep clean than a flat stainless surface. Although stainless steel seems ideal for medical purposes, it is not hypoallergenic.
Many people react badly to nickel, which is present it high quantities in surgical stainless.
It also turns some people's skin green. Silver is used in tableware because of its whitish luster and preciousness. It is not really the most practical metal for cutlery. It tarnishes slowly by reacting with sulfur pollutants, which are present in the air in trace amounts. Pure silver is also very soft because it allows slippage to occur easily.