Well not Go's package manager, right? Go modules came out 2019, Swift 2015?

I wasn't arguing against Swift needing a default package manager, I agree with that. Just the examples you picked to compare with are odd in context. You could compare Swift to its contemporaries like Rust or Zig and come to the same conclusion.

I think you missed it: go and dot net launched without package managers. It was a long time before they had a standard package manager.