I think that "impossible to detect" is not something realistic if camera manufacturers are willing to start adding encryption signatures to their cameras outputs and are willing to vouch for them.
I realize this would still allow fakes to be presented by governments in all likelihood, but not everyone.
Leica started doing this a few years ago in response to the first wave of AI images[0]. Other, bigger manufacturers (Nikon, Canon, Sony as well I believe) have also joined, though with less fanfare. Adobe is in the loop.
As someone with a passing interest in infosec and cryptography, I'm sceptical of the long-term viability of this kind of product; it only takes one person successfully extracting a signing key to undermine the entire project.
[0] https://leica-camera.com/en-int/news/partnership-greater-trust-digital-photography-leica-and-content-authenticity-initiativeYou still ultimately have the analogue hole here - pull the camera apart, splice your own hardware somewhere between the sensor and the thing that adds the signatures (or in front of the sensor).
Pointing the camera at a screen could potentially evade that.
wouldn't that just encourage monopolistic behavior and lockdown of these devices?
they're already locked down as-is.
Who posts raw output from cameras anywhere? This doesn't seem useful outside some niche use-cases (like security camera footage). At a minimum just about every recording is going to be re-compressed for streaming.