There are farms of people who literally sit around all day and solve CAPTCHAs - there's no surefire way to address this problem and it usually ends up in an orc

There are farms of people who literally sit around all day and solve CAPTCHAs - there's no surefire way to address this problem and it usually ends up in an orchestration of reputation-score tooling (including making a user fill out a CAPTCHA) to fingerprint a bot. If you're good at spoofing all of that fingerprinting you'll blow straight past them - it's all client-side in-which you have control all the way down to the bits and bytes.