Getting Things Halfway Done

I'm reading a book at the moment, "How to Get Things Done" by David Allen. Now that is not it's original name. It's generally known as "Getting Things Done", but for some reason, the title was changed for the Australian, and possibly other, markets. Australia was the only one I noticed on Amazon though. All the references in the book have been changed from Getting Things Done to How to Get Things Done.

I have no idea why they changed it, but if they've gone to all the trouble of doing so because of perceived cultural differences between Australians and American, why didn't they change the spelling of, for instance, "organize" to "organise" throughout?

I have no problem with them renaming this book, but it's like they've stopped short.