> anonymous
Pick one. reCAPTCHA is based on tracking users in countless unknown ways, which is why it's basically unusable with any kind of known proxy (i.e. Google usually classifies Tor users or users from 3rd world countries as bots by default). It may be stopping "dark web hackers", exactly because it's unsolvable by anyone Google decides to be a potential threat, and that also includes bots.
Honestly, I feel like everyone would be better off if instead of reCAPTCHA, websites just used some service that automatically blocks proxies. That way you aren't getting Google to track legit users, and still forbidding potential users from joining who would otherwise be blocked by reCAPTCHA. And maybe if Google isn't watching me on your website, perhaps I'll be more inclined to visit you from my actual IP.
Or just use something that is actually solvable by humans, like hCaptcha. Cloudflare did that and it's wonderful (well, compared to reCAPTCHA), I can solve it in a few seconds, unlike reCAPTCHA which I can keep clicking on for countless minutes only to get told that "my network is sending too many requests" or something.