Comment by potamic

Many a time I receive multiple challenges on a site despite having selected all images perfectly, and can't help but wonder, "Hey, are they getting me to do more work than necessary because they're running behind on their labelling backlog?". There's definitely a conflict of incentives in this case. If you're a website owner, you're better off choosing a different service which doesn't have adverse incentives, otherwise it can affect your site experience. And please don't put captcha on GET requests. Use a CDN if you're unable to handle bot load. And don't even get me started on CDNs that throw captcha.