alt Hacker NewsThere is a whole industry of CAPTCHA solving services that mostly use humans in places where labor is cheap. Prices per reCAPTCHA vary somewhere between $0.001 to $0.002 on one of the popular ones. It doesn't require much sophistication to use it. For around $50/year you can spam a website with 100 comments per day, assuming it requires a CAPTCHA to be solved per comment. This pricetag may leave the average script kiddie out of the game, but if your spam is earning you money somehow then this becomes easily profitable. I don't believe these services are "edge cases"
I'm aware of that, but CAPTCHAs are still a hurdle for most low-effort operations. I'm not so certain that ones using mechanical turks are not edge cases, since they would typically target the largest and most popular/profitable sites, and wouldn't bother with smaller websites.
Besides, CAPTCHAs shouldn't be the only protection against spam. There should still be content moderation tools, whether they're automated or not, to protect when/if CAPTCHAs don't work. Larger websites should know this and have the resources to mitigate it.
So saying that CAPTCHAs aren't worth it because they're not 100% accurate or effective is the wrong way of looking at this. They're just the first line of defense.