Well, that's because Go, as per design, is quite limited. Its type system is lacking things Rust has. The languages have (had?) different goals. You can see one past example in generics. How long it took to finally drag the Go developers to implement them, coming to recognize their usefulness, instead of sticking to the rather limiting "No we want the language to be very simple so that everyone can understand and use it." attitude. Rust has been designed with that safety aspect as one of its primary goals and that will incur some cost in being less simple.