I'm wondering if this might not be illegal under several countries' data privacy laws. Users need to be directly and visibly be informed, if and when data of theirs will be transmitted to third parties. As Google's ReCaptcha is based on tracking what websites you visit, what search terms you enter, correlating this data, and comparing this tracking profile of yours, it's quite problematic that the user doesn't even s…
I can see this easily addressed by a TOS. Even the subtle ones like "clicking that button means you agree to [link to TOS]" covers it, no?
You actually have to make a separate, opt-in checkbox, directly informing the user what will happen.