Returns sent with no protective packaging, just a label stuck onto the packaging

Hi, does anybody else have experiences with customers returning products by simply sticking a postage label onto the product with no protective packaging? I seem to recall as a buying customer seeing a returns process which suggests no packaging is needed. Is that true? Why would Amazon do that? My products have shrink-wrap around them, so when a customer does this, the label cannot be removed without removing the shrink-wrap, which then makes the product a used/opened product. I don't understand why Amazon suggests customers can simply return a product by attaching a label to it and sending it. Am I missing something please? Thanks