What I mean is that these annotations are going to prevent compilation if you get them wrong, but the compiler's type inference is good enough that you only need to provide types when there is ambiguity.
That means most of the type annotations written exist because developers find them useful for documentation.
> 95% of annotations in the average haskell codebase are unneeded for compilation
Like type aliases. They are not distinct types, so the compiler doesn't (can't) check that you're using the "right" name.