My point is that if someone like me can return almost half their items and Amazon doesn't care at all - then it's extremely unlikely the people are being banned from Amazon services for returning a USB drive.
As well another question is what is actually doing (or not doing) Amazon about the USB sticks/drives issues, the return rate of that should be something like 90% assuming that 5% of buyers fail to realize that the size is much smaller and - still say - another 5% buys them "for later use" and do not test them on arrival.
In a traditional brick and mortar store there would be someone monitoring the return rate for defects on any item for sale as - besides the loss of perceived reliability - there would be objectives costs for handling the returns.
Say its Wednesday night and I'm starting to design a project I'm doing over the weekend but I'm not done yet - and realize I will need 8mm shafts but not sure the length of my design. I just buy 3 or 4 versions of the product with the approximate length I may need and then end up just using the one my final design calls for and returning the others.