"Unfortunately, because Google is so tight-lipped about reCAPTCHA's privacy implications, we're left to guess which data sources it uses to determine your humanity (or 'risk score' in reCAPTCHA v3)" Yeah, reverse-engineering that should be a priority. I mean it's not OK that people are just taking their "trust me" attitude. The fact that web of trust concept is entirely being ignored tells you they want a centralized solution with one API to rule them all - they're basically 1990's Microsoft all over again!
"Google maintains that reCAPTCHA is only used to fight spam and abuse." Until it's not. Or until they define abuse in a way that includes "tracking evasion". Or start using it as their own personal Carnivore to out TOR/I2P users, leakers, etc.
It's time for an addon (or filters for uBlock Origin) that just puts ReCaptcha in the timeout corner until you actually need to login. If they start blocking people for that, going to be some huge lawsuits for the levels of coercion involved, even if 'insulating' themselves by getting a third party to help them do it. Realize: There's government websites that require it.