How corporate greed loses copyright holders’ sales

A while ago, I looked up a book that I like on Amazon’s Kindle store, to see if I could get it for my Kindle. Sure enough, they had it, but they wouldn’t sell it to me. Instead, I was met with this message:
 
To my mind, there is no good reason for this. There is, however, a very bad one: Corporate greed. Because authors generally have publishing deals with different publishing houses in different regions, they lose sales. By the same logic, I should not be allowed to buy a book in the US, and bring it back with me, or order the paperback from Amazon, yet I am.
 
Ebooks are by no means alone in having this kind of problem. The best example I have, is regions on DVDs and Blu-Rays. The historical background is the divide between NTSC and PAL; two different systems for video tapes. NTSC tapes would be recorded and played back at 60 frames per second, while PAL tapes would be recorded and played back at 50 frames per second. The reason is simply that the electrical grid in the US transfers AC power at 60 hertz, while the grid in European countries transfers AC power at 50 hertz.
 
Now, while there was a good reason way back when, there is no good reason now, and this silliness needs to stop.