Most important information is textual, and there's really nothing at all that binds text to reality. So we have laws about fraud and libel for important matters. Trust is a hard problem! But we're working on it, and images were never much of a solution to it anyway.
Most of the time, we just don't care. Many stories are untrue; explicitly fictional. Some of them are untrue in ways that could emotionally damage others (gossip, insults). That's just a part of social life, to be mitigated socially, not judicially.
Images are going to be just like text. Let's all just embrace that already. You can't lie any more or less with them than you can text, once we all (inevitably) stop trusting them as though they were difficult to fabricate. There's a little turmoil coming, but there's less if we all just decide to get over it now rather than cling desperately to the idea that images are somehow more deeply intertwined with the real world than text is.