The Scala spec is much shorter than the C spec… Also it's of course much shorter than Rust, where nobody has a real issue with its complexity, at least nobody is complaining really loudly.

The C and Go specs are actually extremely involved, long, and complex given that the languages almost don't have any features at all.

But comparing language specs isn't a 100% fair metric.

One should instead look at formal language semantic definitions written all in the same way.

If you look at these you will for example learn that the C semantics are much more complex than for example Java.

Check out https://kframework.org/ to learn more. (A list of semantics for different languages can be found on the "projects" sub page).