Of course, Go itself is completely unsearchable, so you always have to search for Golang, which means that thee mut be hundreds of pages that get missed.
As for Java, Python the context in the page likely to point to its intended audience (and it helps they have been around for ages etc). Otoh, " go " is likely to be used in a lot of literature, including other programming related texts.
Try searching for something with clojure, and then try go -- the quality of results is usually substantially different, and my unsubstantiated hunch is that not all of it has to do with lack of go-related content.
Seems to be getting better though..