How many Wikipedia articles are one sentence saying "this is the answer"? None. If anything they're padded out to excess, detailing the different perspectives about any particular topic, complete with referencing and footnotes.
I was going to take issue with you're "this is the answer" description but sure enough, on the featured snipped "About this result", Google interchanges the word "answer" and "result" pretty arbitrarily:
When a user asks a question in Google Search, we might show a search result in a special featured snippet block at the top of the search results page. This featured snippet block includes a summary of the answer, extracted from a webpage, plus a link to the page, the page title and URL...
Wikipedia came to mind when this topic of 100% accuracy came up, a metric people seriously think Google needs to hit in order to not cause mass hysteria, it seems. Wikipedia is constantly updated because the information is curated by humans. Humans have the ability to lie, omit facts based on beliefs, fudge numbers to paint a specific narrative, and so many more egregious examples of ways to mislead those who would use the resource. I understand having high expectations for things but just like with anything fact based there needs to be a level of skepticism and self policing of what we allow to become things we know to be true based on our own acknowledgement.
This is something I feel long time internet users have built up a tolerance to and an eye for. Of course I understand wanting to hit that 100% metric for those unfamiliar with the concept of others steering folks in the wrong direction purposefully but how can we honestly draw a defined line in the sand to gauge a systems usefulness? Especially when that system's data is based on the concept of human knowledge, an ever changing, rapidly developing, and hotly contested part of the human experience?