I suspect AI text detection has actually become easier, as chatbots today have been heavily finetuned towards a more distinctive style.

For example “delve” and the em-dash are both a result of the finetuning dataset, not the base LLM.

You are forgetting the human mind accounting for this and adding "write this like a kinda dumb high school student". I just did a little test between a copilot essay and the same prompt with "write this like a kinda dumb high school student" and it reads like an essay i would have written.

In the brave world of the future you too will be able to get a C- with very little effort!

That's where the humanizers come in. These are solutions that take LLM generated text and make it sound human written to avoid detection.

The principle of training them is quite simple. Take an LLM and reward it for revising text so that it doesn't get detected. Reinforcement learning takes care of the rest for you.