Someone orders it, takes out the headphones, replaces it with an object of almost identical mass, returns it, amazon automated returns service notices it's very slightly a different weight, if the margin on the item is greater than the total cost all of the already completed returns flows plus the cost of one additional return times the probability of the next customer returning the item they just put it back into the warehouse, otherwise they burn it and fire all employees at the fulfilment centre*.

Basic logistics.

_{*Obviously there are additional variables such as the number of current reviews, probability of a negative review, cpu time to bury the negative review with synthesised positive reviews, but you get the idea.}