Recently on a new installation in OC 3.0.2.0 Google reCaptcha I've notice is not being enforced and I'm able to bypass any of the scenarios were the captcha is required and not used.
I have also tried with the Basic Captcha and this one Works correctly.
The secret and the key are added correctly on the admin, the reCaptcha is selected correctly on the "system>settings>option>__" and selected all the checkboxes..
The reCaptacha shows accordingly and the Red * as a Mandatory but I can simply Bypass this verification without the thick on the checkbox and continue with the registration - email etc...
*UPDATE*
FYI
This is common is you are logged in the account from which you took the captcha credentials from and the same Browser (Chrome) - will automatically let you ByPass it (no user action).
As soon as you log out and clear all the cache and try again It won't happen and you will be enforce to reCaptcha to continue.

Regards,