In some cases an AI will make a weird word choice. So do a lot of humans. Sometimes AIs are needlessly wordy. Um...so are a lot of humans. Rinse and repeat. AI detectors are useless. The AIs are training on human writing, so they write fundamentally like humans. How is this not obvious?
AI detectors are useless, you're right, but for the same reason AI is unreliable in other contexts, not because AI writing is reliably passable.