Because not all of the jurisdictions allow it, even if there's authorization. If one looks at British Columbia, it simply says it's not allowed to be used by any political party “for political party advertising, election campaigns or any other politically partisan activity”.
So it doesn't matter if Marlene Jennings says “Yes, you can use that clip of me in the House or in committee” and if I tell my party or my official agent they can use it: I'm not allowed to do that in British Columbia.