For example: I have a number of small Go projects that are incorrectly categorized as CSS or Javascript. One such example is a project explicitly designed to be a Go webserver that you can just "go get" (or git clone) and run immediately, with no extra setup, sort of like Twitter Bootstrap, but for the backend: https://github.com/ChimeraCoder/go-server-bootstrap
Because it self-hosts the Bootstrap files, and because the lines of Go code required are relatively small, less than 5% of this project is detected as being written in Go, even though I didn't write a single line of Javascript or CSS myself for the entire project.
(Yes, I know I could pull in the Bootstrap, etc. from a CDN, but this is just to illustrate the limitations of an automatic language detection model that the developer has zero control over).