This has become just another one of those seemingly endless debates on the same point where a subset of posters apply a halachic analysis to how yidden should behave in their daily lives, with a specific reference to their interaction with goyim. From the other side of the debate are those who are viewing the issue from the lens of a more common sense, non-legal perspective which might subjectively be called “ethical”. Bottom line: Just because something might arguably be “OK” al pi halacha, that doesn’t mean its something that SHOULD be done.
Yes, most Amazon sellers will allow returns for ANY reason (or no reason) but exploiting that policy to use something without payment is not how some of us believe a Jew should behave. YWN frequently highlights stories about yidden going to great lengths to return lost items to their owners (yidden and goyim) and what a big kiddush hashem it was. In some cases, it was a yid risking his/her life to save a goy and what a kiddush hashem it was. I see it no less of a kiddush hashem for yidden to act ethically in their financial interactions with goyim (and thereby forego opportunities to gain monetary benefits such as the Amazon scenario). If you don’t want to call it a kiddush hashem to show that yidden are ethical and don’t engage in the stereotypical behavior that forms the basis for long-standing anti-semiotic tropes, than just call it “the right thing to do”.