I just read Reid’s post on mail-in rebates, and I couldn’t agree more. They are stupid. I have been offered that same contact lens rebate for two years in a row and never bothered to fill it out. I think he’s right about the motive — the companies are hoping you won’t go through the inconvenience of jumping through all the hoops they set up. According to Wikipedia, it offers the company some other advantages such as earning interest on the additional money until the rebate is processed.
As for how much money they spend on processing? Probably not much. Many of those work-from-home ads you see online, with vague promises of “being your own boss” and pictures of big houses and wads of cash are for gigs processing rebate requests. My guess is they don’t pay very well.