[jmilica]

I have no idea if this particular subject has been discussed before but I am really interested in opinions on Mobileread.
When I first got my first Kindle, I had no idea of geographical restrictions on ebooks and the price differences (not to speak of formats). I understood later on that certain ebook's availability depended on publisher's rights etc, which seemed reasonable to me.
But even after learning a lot on ebook industry - and much on this forum too - for the life of me I cannot understand the ebook geographical price difference. Namely - I tried buying a book on Kobo today - same book (classic fiction, originally published in 19 Century) - same publisher (Penguin) - costs differently in US, UK and India (approx. more than 10 $). Then, in US and India you can easily apply the latest coupon code and get 80 or 75% discount, but in UK shop you can't apply code?
Why is it that a certain publisher sells the same book of the same author in one country in this case for around 3$, while in another country at the same time sells it for more than triple the price?