Empirically, we've passed the point where that's true, for someone not being lazy about it.
https://www.astralcodexten.com/p/how-did-you-do-on-the-ai-ar...
In other words, someone willing to tweak the prompt and press the button enough times to say "yeah, that one, that's really good" is going to have a result which cannot in fact be reliably binned as AI-generated.
I mean, no? None of the AI-generated images managed to be indistinguishable. Some people were much better than others at spotting the differences. He even quotes, at length, an artist giving a detailed breakdown of what's wrong with one of the images he thought was good.