The fact that AI-generated content is so difficult to detect suggests that progress in this field has been extremely rapid. It is remarkable how quickly advances are being made in this space. I have heard that some news outlets are already using AI-generated content in their publications, and it is easy to imagine that in a few years they will be so capable that they can produce content that is indistinguishable from real human writing.
Currently, AI is capable of writing articles with the quality of an amateur copywriter. It is not difficult for me to measure the quality of articles, despite the distinction between being a robot or just a bad writer being unknown to me.