Amazon follows a long line of huge-volume retailers into "not afraid to be the asshole" territory. Unless it's the case that it actually costs Amazon money to

Amazon follows a long line of huge-volume retailers into "not afraid to be the asshole" territory. Unless it's the case that it actually costs Amazon money to offer books at the prices that IPG wants, this is a pure power/spite/warning play. And I very much doubt that it costs them money.