If the AI creates such volume as to make an individual's image visible to millions in another country for example, then the individual's lack of knowledge means pursuit for permission is highly unlikely. Then it's a de facto conclusion that it was all right to use it, when in fact, the individual never knew it was their own image being used someplace else. Totally not fair.
Unless they get caught, no advertiser will have incentive to ask for permission.
That's why we need rules.