I have a certain advantage being an author here in Canada. I am sort of self-published. I have created a very (very) small publishing house, I’m not the only author published by my company, but there certainly aren’t many. However, having created this publisher I can get ISBN numbers from the Government of Canada. It’s as many as I need, anytime. I submit a request and five minutes later I have an ISBN to use.
IT’s a major support, and one that I think is sorely lacking for Americans. Of course, our governments co-operate, so an ISBN from Canada is recognized in the US, and everywhere else in the world really.
I only do ISBN’s for books. Novels, short story collections, or textbooks (my company publishes one of those, I’m not the author). Short stories on their own don’t get ISBN’s… because I won’t ever bother printing them, and I don’t care about discoverability outside of Amazon itself, which doesn’t require an ISBN at all.
Novels do require ISBN’s, of course. Well, not really, if you only sell on Amazon you don’t have to use one. Also, you can use one assigned by Amazon, but that means Amazon becomes the official publisher. It might not make a difference, but it might as well. For me, because the ISBN is free I don’t have to worry about it. I just create a new ISBN and publish my book as I want.