Is it!? Theymos said he paid $0.10 for captchas (maybe that was with the old service though). I always thought the free captcha was just a sales technique to start with although it is bad enough that they probably kept it free.
That figure just seems wrong even if there ever was or will be paid captcha services. We have tens of millions of rolls a day and although I don't know what percentage of those have a captcha those figures are going to add up to an astronomical amount.
Google is in it for the data. If you're logged into your Google account they track where you are doing reCAPTCHAs and know more about what sites you visit and have accounts at.