Well, since the Prelude was never changed to at least add an alternative headMaybe, perhaps it was not seen as a deep enough mistake.

Yes, I am aware that the Haskell community generally tries to push more guarantees to compile time, and that Haskell's ease of defining and using new types equivalent to existing ones but that signify some property helps a lot in this.

Still, there is some limit to this. For example, you have many libraries adding measurement units for Haskell, and many libraries doing linear algebra. But you won't find too many people doing linear algebra with measurement units, because the types of intermediate results explode too much (e.g. a type-safe unit-of-measurement matrix multiplication of 3x3 matrices has 18 type parameters, with complicated restrictions between them).