I believe what the spammers have started doing is presenting these captchas to human users on more illegitimate sights, such as those to watch free sports broad

I believe what the spammers have started doing is presenting these captchas to human users on more illegitimate sights, such as those to watch free sports broadcasts, etc to gain access. The user solves the captcha for the site which then uses that solution to fool the actual Google captcha.