Write a check on a dollar account to a dollar account in a different country (in this case from the US to the UK). The check takes up to three weeks to clear. Even a wire transfer can take several days.
Try to get photos printed using Apple's iPhoto printing service when you are in a different country. Perhaps because you have relatives there. Apple UK won't accept a US registered user as a customer.
Try to gift an iTunes download (following the same approach as the iPhoto example above). Doesn't work.
Buy a DVD collection when you live in one region and then move to another. The DVDs won't play on most locally bought machines (I know there are ones that do work and for some reason they are the cheapest in the store).
So why all this Regionalization of DVDs and country specific Digital Rights Management? As far as I can tell, it is designed to prevent internet shoppers from getting a better deal on a foreign site. There's probably more to it than that. Meantime, I do have to wonder how many sales have been lost as a result.