If you are in the UK you will need to go to Amazon.co.uk and then search for the title. Still available at zero cost. Any idea why this "Chinese wall" exists f

If you are in the UK you will need to go to Amazon.co.uk and then search for the title. Still available at zero cost. Any idea why this "Chinese wall" exists for Kindle? I can buy print books from Amazon.com (sometimes technical books are cheaper there even allowing for the increased postage) but not digital ones.