Not only that, but Google doesn't use language-provided build systems anyway because it's important (to enable many other useful dev tools and practices) that e

Not only that, but Google doesn't use language-provided build systems anyway because it's important (to enable many other useful dev tools and practices) that everything is built using blaze (the thing externally released as bazel). So really, Go's decisions about modules, vendoring, source layout, and the "go" command itself are all kind of irrelevant within Google. (The underlying Go compiler is used of course)