Scala's type inference is not complete; it is marketed as a way to "omit certain type annotations". One of the reasons why Hindley-Milner is so influential is because you really don't need any type annotations: the inference algorithm always works.

As for DOT https://www.cs.purdue.edu/homes/rompf/papers/amin-wf16.pdf DOT is an explicitly typed calculus (similar to System F), for which no attempts at type inference are made. So... they're not really comparable at all.