Google didn't invent this: Luis von Ahn, a CMU grad student did in 2000. Google acquired it in 2009.
https://www.cylab.cmu.edu/partners/success-stories/recaptcha...
https://www.cylab.cmu.edu/partners/success-stories/recaptcha...
The original recaptcha was only text from book digitization projects.
To be fair, if you use google maps, and don't have any ethical issues with helping googler, you do get a return on investment, in that you get improved ML capabilities and improved address recognition in google maps.