Detecting AI-generated text is an adversarial process. Meaning there are going to exist people interested in avoiding detection. This just ensures there is never going to be a reliable solution. There will be some solutions but none that will be reliable.
We still have counterfeit banknotes and email spam. Seems like super easy problem to fix but there are always some banknotes and always some email spam that avoid detection. And this is simply because whenever somebody finds a way to close the current hole, somebody else finds a way to open another.