Ha! I guess I'm less human than expected, and finally I understand why I've failed sooooo many CAPTCHAs over the years :)

Thanks, I really never knew!

I actually found I had more success with reCAPTCHA when I made myself think less about what the answer was.

I also learned this trick that a lot of the questions have a standard number of answers – e.g. there are always three buses, or fire hydrants, or whatever – so once I've picked three, I'm done. (There often is a fourth ambiguous case, which it accepts but doesn't require.)

I think I'm failing the captcha by not being sufficiently pedantic. It genuinely never occurred to me that a coach might not be considered a bus by the algorithm (where "algorithm" is presumably "distilled responses of many thousands of other humans")

This comment doesn't help the pedant