re: someone was unable to get past that captcha - this reminded me a story I heard back in ICQ times about some human who couldn't pass anti-bot question: "What planet do we live on?"
I remember a friend's con-group forums who had an issue along these lines - the anti-bot question was "What is the brightest thing in the sky at noon?" the expected answer was "the sun", but some guy got stuck because he was answering "Sol". Since they had an IRC channel the issue was relatively quickly resolved, but it was an in-joke for some time.
The key takeaway is that if you have a second line of communication, humans can use it but bots won't - "Issues registering? Contact someemail or see us on IRC/Discord" can do wonders.
Fair enough… one can only speak for oneself, after all.