Flagging you as a robot incorrectly would be less of an issue if it was just Google doing it.
Unfortunately, lots of other websites use the API. There are plenty of Wordpress plugins that add Google's recaptcha to comment forms and I've seen it elsewhere.
It could become a de-facto standard and at that point the issues - in particular for accessibility - become critical. If it's more likely to pop up if you're disabled and using things like screen readers then it's discriminatory.
If nothing else, it'll be something new to keep the EU busy with Google...