I just posted my first answer on this site, sharing a solution I've found to a problem that was not yet listed. Given a high enough reputation score on another SE site, I received 100 reputation bonus upon joining this site. However I was still being asked (for the first time ever in using this network) to fill out a third party CAPTCHA before my answer was posted. Why did this happen?
Note that it uses Google's CAPTCHA service, logging my visit here to a company that has already more than enough data on everyone. Now I don't mean to start a discussion about how bad or benign this is (as a developer I fully understand the choice to use that service), but because of this I am more curious to hear the justification for asking an active, logged-in user with a good reputation.