"We evaluated a number of CAPTCHA vendors as well as building a system ourselves."
and
"We worked with hCAPTCHA in two ways. First, we are in the process of leveraging our Workers platform to bear much of the technical load of the CAPTCHAs and, in doing so, reduce their costs. And, second, we proposed that rather than them paying us we pay them. This ensured they had the resources to scale their service to meet our needs. While that has imposed some additional costs, those costs were a fraction of what reCAPTCHA would have. And, in exchange, we have a much more flexible CAPTCHA platform and a much more responsive team."
So Cloudflare are basically cloud hosting hCAPTCHA's services. I wonder why Cloudflare didn't just buy them, as it seems like it would be a win-win with getting an excellent CAPTCHA service, and not have to build it themselves?