Lately I've been getting reCAPTCHA prompts all the time even though I'm not browsing in incognito mode and haven't cleared cookies. All I'm doing is running a very basic ad blocker, using Safari (which blocks third-party tracking), and very rarely loading a Google site. The most interaction I have with Google is when I end up having to use my corporate Google account as SSO for some other site.
Given that I'm not doing anything unusual, it really feels to me like reCAPTCHA, for all its complexity, boils down to "what's your history using Google software? Oh you rarely use it? I'm gonna give you a captcha". It didn't used to be this aggressive, but it's really ramped up in the past few weeks.