The simplicity of it is logic defying. It used to be that you had to find crosswalks or move puzzle pieces or type blurred letters and numbers, but NOW all the sudden I can just click a box and HEY!, I’m human?
That’s hardly the Turing Test I’d expected.
To elaborate on point 1, it’s about uniqueness and timing of the path the mouse takes to click the checkbox. If it’s too straight or consistent it will red flag you.