This is just speculation. People generally report high productivity using Go. Some copy-paste can be a small price to pay over having overly complex code.
I don't know how much time is lost on project development because code is too complex. Rust may be fine if that is the only thing you do.
But if you work on different systems it can be a real productivity drain to deal with a complex language like Rust. Getting up to speed after break can be difficult.
I have experienced so many times with some of these really strongly typed statically typed langauges that I can fix a problem in a dynamic language faster than I can figure out what the compiler is telling me.
Complexity has a cost, which a lot of the fans of complex langauges fail to acknowledge.
I am not saying Rust is bad. Just that there are tradeoffs and that it is not silver bullet. I also don't believe in languages as having universal benefit to all people. I have been programming long enough to have observed how different people handle different types of languages differently.
A language which works really well in your hands may not works so well in the hand of somebody else. It is probably a contributing cause to why we have so many languages. People work in different ways and benefit from different programming styles.
Go is fine in that it is a very broad based lowest common denominator. You can make almost anyone decently productive in the language. Rust is more of an elite language. A small group of clever developers may get very productive with it. I doubt it works well for the average Joe developer though.