Requiring the implementation of a Go interface is less powerful than requiring a trait.

It reminded me of early years of Rust where people saw traits and asked, well Java had interfaces for many decades, what’s the innovation?

I'm not sure you can really argue that Rust's traits are innovative. Haskell typeclasses, OO-style abstract interfaces, and C++-style associated types were already well-known and well-established features. The particular mix of those features in Rust may be new, but the same could be said for Go's, or really any programming language's, particular mix of features.

You're right of course that traits are more powerful than interfaces. Go simply isn't designed to satisfy fans of elaborate type systems. This can be frustrating at times, but it also means that you don't have to deal with overarchitected library code like this: https://github.com/marshallpierce/rust-base64/issues/213 (Yes, you can overarchitect code in Go too, but the simplicity of the language, and the model of the stdlib, do tend to discourage this in practice.)

I've never written Rust professionally, but I did have a Haskell job for a couple of years. IME the sophistication of the type system is a double-edged sword. Sometimes it lets you concisely express important invariants; sometimes you end up spending way too much time writing elaborate types for code that isn't really doing anything very interesting. I understand the appeal of fancy type systems. In practice, I get a productivity boost from any kind of basic static typing, and then rapidly diminishing returns from the fancier stuff.