Demanding responsible behaviour from everybody is not going to work. Some people don't care about negative externalities that much and it's enough if only a few of them decide not to play ball. So either grandma needs to adapt which will upset some people or distributing the tech should be regulated/prosecuted which will upset another group of people.
I think either way grandma needs to adapt though since Russian scammers and trolls are still going to run scams with fake voices.
how very politically correct of you to pretend it's Russians who scam your grandmas