Comment by koalaman

I'm not sure reCAPTCHA is really trying to detect automated vs human interaction with a browser. The primary use-case is to detect abusive use. The distinction here is if I automate my own browser to do things for me on sites using my personal account may not be a problem for site owners, while a spam operation or reselling operation which generates thousands of false accounts using automation is a big problem that they'd want to be able to block. I think reCAPTCHA is tailored towards the latter, and for it not to block the former might be more of a feature than a bug.