Steam

They probably hold funds in escrow until games are outside the refund window before paying the devs, it would allow them to do this pretty easily.

I imagine they've had enough refund requests for games that went on sale shortly after purchase that it made sense to them to automate it. Still, if it were me I'd be automating the ticket processing rather than the refund itself to at least screw over a, most likely, large portion of the users that didn't notice.