"I feel it's unusual that of all the places in the world, its predominantly in USA where these terms of 'some origin - American' are used."

Actually it's a very common and long-established practice in Canada, and in this case, it's NOT due to American influence. It's so accepted that you often hear the term "hyphenated Canadian" in discourse having to do with issues of multiculturalism, immigration, ethnicity, etc. Although, to be sure, it often appears in a negative context, as in someone saying, "I don't want to be a hyphenated-Canadian ... "