I got an obviously-AI voice agent spam call yesterday. Had a bit of fun getting it to answer trivia questions (when was the treaty of westphalia ratified? answer in a rhyming couplet) as a precondition to handing over the keys to my bank accounts.
Perhaps the future of captcha is anti-captcha. What agent can resist responding with a rhyming couplet or inverting a binary tree?
Downside is they most likely are using stolen tokens, not paying themselves so it cost them next to nothing.