initializing vars in Golang

init.md

In this simple golang example it appears that we don't need to initialize the wg variable. Why do we do this:

var wg sync.WaitGroup
func main() {
        // do some stuff
        wg.Wait()  //     // blocks/waits for waitgroup
}

instead of this:

var wg sync.WaitGroup = sync.WaitGroup{}  // is this initialization implicit, and why?

func main() {
    // ...
}