Don’t quote me on this but I believe the law that makes you a Canadian citizen upon birth was not enacted until 1977.
1947, actually. Prior to this there were no Canadian citizens, we were all British Subjects. IIRC In 1977 the law was changed so that we are no longer British Subjects.
My friend, born there of American parents in 1948, has dual citizenship.
You’re incorrect on this. Canada has had birthright citizenship since about 1945. What has changed is the status vs the United Kingdom, and the status of those grandfathered before 1945 who wished to keep their British citizenship.