I think the thing that you're missing is a teenager is generally not going to be able to make a photoshop that's believable, whereas they can currently generate totally believable pictures and even video using GenAI. Sure, some will realize it must be AI, but some won't and no matter what, the theoretical 13yo is going to feel just as threatened and violated.

The problem is that no regulation is ever going to work on the endpoints, so things like age-verification are pointless and an invasion of privacy. The only thing that will work is going after the companies, their training data, and the infrastructure. There will be stuff out of the country's jurisdiction, but we already have laws handling that type of thing, and while imperfect, they do draw a line. And yes, local models will still be a thing, but you don't enforce against the creation, you enforce against the trafficking of such images. If some modern day teenage da Vinci painted a near-photorealistic nude of a classmate, he can do that. But the minute he shares it, it comes under existing laws in sharing such images. Why should GenAI be treated any differently?