There's no way that you can reliably get 90%+ accuracy on complicated captchas with automation. With automation you might only get a 30% success rate on a highly obfuscated captcha, but since there's no marginal cost for each attempt you can throw as many attempts as are required to crack a particular image. Some stuff like the more difficult recent versions of recaptcha just basically can't be cracked because they're barely readable by humans, let alone machines. No one would pay per attempt for something with 30% accuracy.
Your average rural Indian captcha cracker earns $2-4 US for a full day's work and that's considered good money for them.