You have done nothing to answer the GP.
How does Google determine if the captcha should be shown?
What are the "adaptive captchas" that are shown to suspect users? A demo would do a great job here.
How does an invisible captcha "create value by applying human bandwidth" if the premise is that humans never see the captcha?
Really?
> It doesn't explain how it works nor a demo page
Imagine a web form without reCaptcha. Do you really need a demo of that?
> nor the reason behind why it went invisible.
Because Recaptcha had an annoying, bad, terrible UX.