[hombre_fatal]

The vast majority of users never see a recaptcha puzzle when you're using v2's invisible recaptcha.

[SquareWheel]

And 0% of users see it if you're using reCaptcha v3.

[xur17]

It never presents challenges to users, but instead just buckets them into bot or not bot?

[SquareWheel]

Almost. It gives a botness score to the server, and it's up to the website to decide what to do with that score. They can pick a threshold to approve, reject, or apply stricter verification to.