Another silly question on regional release's

[moggy]

I suppose this question has been asked once before, so i'm sorry for repeating it to those who have posted replies to this question in the past.

My question being when i have been searching other areas of the globe for new blu-ray titles, there seem to be such a difference in release date's.

Just as an example A Bridge Too Far is coming next month to Japan, it is not out in Europe, Aussie Land or the U.S until later in the year, as far as i am aware, so why not a universal release of all titles?
Is it due to copy rights or some other reason?

Thanks for any replies, as i will sleep better tonight knowing.