You're building the AI of the future:

http://www.commitstrip.com/en/2018/09/24/trolling-the-ai/

If you click randomly eventually the computer gives up and thinks you're a really stupid human and takes pity on you.

Really? If so, I'll just do that from now on. I'd rather waste a few extra seconds than work for Google for free.

I've found sometimes the robots get really upset at your terrible performance and will ask you a lot more frequently, but eventually tire of asking new questions and are like "Sure, whatever." You'll get prompted a lot more often with the usual captchas though.

same. nothing more infuriating than failing a captcha three times....somehow.

Why get one person to do one unit of work to train your AI for free, when they could do three units of work for free?

That kind of captcha seems unusable to me as well. No idea what could be used instead.