There is an overlap between module and class namespacing through static members and functions. Zig sees this and says "let's only have the latter" (on structs), which means among other things that in Zig a file is a structure. Most other languages says "let's have both".

In C3 it goes the other way despite having methods, and says "let's not allow static variables or methods".

This also goes hand in hand in the language approaches between open/close. Zig is very strongly "closed" and C3 is very much "open" (adding methods to types anywhere, appending to modules anywhere etc)

It's an interesting contrast that leads to very different code layouts.