This doesn't make sense. reCAPTCHA certainly does what it says on the tin. But the way it does it has almost nothing to do with the challenge the human sees. It's all behavioral analytics, including leveraging Google's collected data to determine how likely a user is a bot before they even load the page.

I'm not denying reCAPTCHA is a source of training data for Google -- surely there's no particular reason that every single reCAPTCHA V2 challenge is about identifying traffic objects, and it's not like Google is building a self-driving AI or anything.

But that's the business model, not the core feature.

And, that training data isn't just given to the developers of captcha solving bots.