US… UK? and Beyond – What is the issue with eBooks outside the US

I am growing increasingly frustrated with Amazon right now.  So much so that I putout a feeler on social media to see where readers were getting their ebooks from (Kindle or iBooks).  The unanimous response was Amazon Kindle – which frustrated me even more because of the problems I was having. I recently got wind of something I was ignorant about and maybe I still am.  I friend from Canada reached out to me not too long ago informing me about one of my books not being available in Canada.  As I looked into it I also realized that this was similar to what was happening in the UK and other parts of Europe.  I have a specific author page in the UK with Amazon, but as I look at the postings, it indicates that they are available in the US and not specifically in the UK. Has anyone else seen this issue before?  If so how did you address this or is it even an issue?  I am curious and concerned as I have been having some major difficulties of late with Amazon and specifically Kindle Direct Publishing which has held up the release of other works I have...