reCAPTCHA switched away from digitizing books simply because it was no longer a good test for human vs robot -- the robots were better at it than humans. "[Goo

reCAPTCHA switched away from digitizing books simply because it was no longer a good test for human vs robot -- the robots were better at it than humans. "[Google's research shows that] today’s Artificial Intelligence technology can solve even the most difficult variant of distorted text at 99.8% accuracy. Thus distorted text, on its own, is no longer a dependable test" http://googleonlinesecurity.blogspot.com/2014/12/are-you-robot-introducing-no-captcha.html http://googleonlinesecurity.blogspot.com/2014/12/are-you-rob... But lots of sites depend on reCAPTCHA, it would have been unreasonable to just shut it down and break a huge swath of the internet because it had achieved the "we could digitize just about any book written in latin script" goal.