reCaptcha is good because it doesn't generate the images itself, so it isn't predictiable, and is easier to integrate.
recaptcha is very predictable, altho not on the sense you expect. You only need to write down the control word correctly. You can write the other one wrong.
After you see a couple thousand of them you can guess which one is the control word and which one isn't...
And yes, only humans can bypass reCaptcha. Bots don't do so good. But they don't need to do good. 1000 captcha solutions cost $1 after all.