France was at least supposed to be a major power, until they got majorly stomped on by the Germans. Italy is a little different, but as far as I know they only became more subservient to Germany only after the war began. Though Italy never really was a major power on par with the others that we think of during the 20th century, the three major Axis powers—Germany, Japan, and Italy—were part of a military alliance on the signing of the Tripartite Pact in September 1940, which officially founded the Axis powers.
France and England have pretty much been the major powers of Europe for centuries, with Germany and Italy having more historic influence that was declining as they went into the 20th century, which was part of why they were looking to reestablish themselves in the first place. It was a big surprise when France fell so quickly. Canada doesn’t have any kind of historic claim to empires like Germany or Italy had, nor does it have any modern claim like UK and France have (they’re still 2 of the 5 permanent Security Council nations with veto power in the UN).
If you’ll notice, the current Allied countries that will be playable in the new version (with the exception of ANZAC) are the 5 permanent Security Council nations: US, UK, France, Russia, and China (though China was in the midst of civil war in WWII).