It is a way to prove you’re human and get useful work out of it. Is your issue that you’re giving free labor to Google specifically or would you have an issue irrespective of the company?
The non-google ones usually waste more of my time, so by comparison I am pretty chill with the Google ones.
My issue is giving free work for free to a company. I see no reason to help them in their chase of a 100B+ market opportunity for free. Some kind of "silly" captchas I might be OK with, if a website chooses them. But sometimes they interrupt (at least while I was using chrome) in the middle of browsing and block off a part of the internet for me until I do as they ask.
This sounds more like you have some kind of malware that's getting you to solve captchas so they can sell the results?