just for giggles, I looked at a NY Times Hardcover Fiction list from the past. May 22, 2005. What can I say, it turned up on the first page of my google search. I ran the first ten books.
4 were not available for Kindle Canada or Kobo Canada
2 were available for Kobo Canada, but not Kindle Canada
the remaining 4 were available for both.
I don't know that it proves anything in particular. I happen to believe that being able to buy books in ePUB format gives me more options, in general. That said, it's just an opinion, and we all know how unreliable those are