Authors who work with Amazon tend to view the Amazon store associated with their country. I'm US American, thus look at Amazon.com. I have friends who are featured primarily at their own country's Amazon presence. We authors forget (at least I do) that our books are sold in those other countries through the other Amazons.
If you're Canadian, you shop at Amazon.CA, if British, you use Amazon.UK, and so on for Germany (DE), France (FR), Spain (ES), Italy (IT), Japan (JP), the Netherlands (NL), Brazil (BR), Mexico (MX), Australia (AU), and India (IN).
Recently, a Brit mentioned reviewing one of my books. I was mystified since I didn't see the review on AMAZON.COM. It shook my brain enough to take a look at AMAZON.UK. By golly, there it was. An outstanding, well-written, and positive review with plenty of detail.
And I had missed it because I usually only look at my "local" Amazon store (.COM). I checked a couple of other countries where I know a book or two was sold. Most didn't have any local reviews, but the product pages did list reviews from the US store.
For authors: Check all the countries where your books are available. You might find a nice review or even a pan you never knew existed.
A big thank you to Dave Higgins for making me look further afield than my own neighborhood. And thank you for the nice review you left on Amazon.UK for one of my books.
You can read all of Dave Higgins' reviews on his excellent blog as well. Now, I'll be a regular reader.