Stainless steel is a classification of steel containing at least 10.5% chromium by mass, you cannot legally market something as stainless steel if it is, for example, mild steel, plastic or wood.
However, within that classification there are an enormous number of different grades, each suitable for different applications. For example, 304 stainless is suitable for building products but will rapidly corrode if used near the sea: coastal areas need 316 stainless.
Your friend may be complaining that Chinese manufacturers use a grade of stainless in applications where American companies and consumers would expect a different type. This may also be illegal if the actual type used were not specified. Notwithstanding, the goods themselves may be illegal as not "fit for purpose".