> For the bulk of Google's visitors, they're good enough

I'm not sure that's true. Just to pick an example, basically any type of product search now leads to auto-generated spam/borderline-spam websites that scrape reviews from Amazon, which are themselves often fraudulent.

I guess you could say that's "good enough" but only in the sense that someone being scammed at some point consents to something that makes them a victim of the scam.

For many searches, you'll see "reddit" autocompleted to the end of the search because Google's organic results are not good enough and people are trying to weed out the spam somehow, albeit in an imperfect way that restricts results to one site.