That is an interesting point, but this already happens on voice calls. My grandma got a call a while ago from someone claiming to be my brother. Said he needed money because he was in a South American jail or something. Luckily shes still pretty sharp, so she hung up and called my brother (he was not in South America) so the ruse was up. She was pretty shaken up though. A video call would be more convincing but only an incremental, not fundamental, difference.
My mother received a similar call, telling her that I'd had an accident.
If you're thinking such an evil persons should be in jail, don't worry, they are! It's them who are in South American prisons using burners or stolen phones.
There's nothing in that link that contradicts what I wrote. My source was an official police alert. I lost the reference, but here is another one from a newspaper (in Spanish):
