It's not so much anger as concern. AI is a tool, but one that can be easily misused.
Lots of people can tell if an image is AI. But a lot of people genuinely can't and it has nothing to do with sanity or intelligence. Gotta be honest, if I had seen that picture outside of this thread it's...
But the permission is the big deal for AI. Most, if not all, AI is trained on images that would normally require permission to use, but without the permission of the originator of the image. Admittedly this is a bigger issue with drawings/illustrations, but its not like professional...