Access modifiers are useful, albeit not for beginners. They're most useful in statically typed languages with good tooling where they keep auto-generated API docs and autocompletions clean.
Static methods are useful for namespacing, e.g.
var instance = SomeThing.fromString("...")
Kotlin has both static methods (or rather companion objects which are an equivalent), and also top level free functions, and when writing it I find myself creating static methods a lot more often for the above reasons.
I probably shouldn't have worded it quite the way I did. Considering I praise Go's access modifiers. What I meant was the "old" way of having lots of them and explicitly having to write them out. I haven't tried Kotlin but it sounds nice.
What I like about Go is the simplicity. Everything inside a folder is a package/module and any method beginning with a capital letter is public while every method starting with a lowercase name is package/module only. Coming from a decade of C# it was such a nice thing.
I do work with a lot of Python where you don't have private methods. I mean, you can set up your corporate environment to "hide" _methods or whatever, but they are never turly private, and static methods are... well... they are basically just namedspaced top level functions.