Why does English (Canada) use American spelling?

Setting the Phone Language to English (Canada) results in spellings like ":Control Center" and "colors" throughout the settings menus and descriptions. No, both American and "British" spellings are not acceptable in Canada. No, some parts of Canada do not use American spelling. The government of Canada dictates that the Oxford Dictionary of Canadian English should be followed and it spells words with "re" and "our" endings.