> If someone writes software that can defeat the captcha, it does mean the security model is broken, but it also means the state of OCR technology (or audio recognition or whatever) has been advanced, and the digitization of books that had previously required human intervention can now be accomplished by automated means.
No it doesn't. reCaptcha only checks one of two words it displays (the other one being what OCRs can't handle themselves), so naturally you only need to crack one and input garbage as the other, thus actually making the world a worse place.
Probably not substantially worse. You would need to be able to tell which was which, since they're not consistently ordered and the "good" one is deliberately obfuscated/smudged/whatever, and, since recaptcha depends on multiple users agreeing on the right answer, you and other attackers would need to be consistent in your garbage in order for it to make it into the canonical book transcript.
No it doesn't. reCaptcha only checks one of two words it displays (the other one being what OCRs can't handle themselves), so naturally you only need to crack one and input garbage as the other, thus actually making the world a worse place.