Copyright nonsense: some publishers restrict ebook editions outside US

Got this message while trying to buy J.K. Rowling's The Casual Vacancy from Amazon:

Due to copyright restrictions, the Kindle title you're trying to purchase is not available in your country: Peru

I have found no way of getting an electronic edition of this book. However, Amazon has no problem with me buying the print edition and having it sent to Perú. Doesn't make sense to me from a business point of view.

Something similar happened with Cal Newport's So good they can't ignore you: no Kindle edition available for Perú.

Update: An 2010 article about publisher's short vision by David Pogue in the New York Times.