the point is that in statically typed languages, the type information is used at compile time, and the computer can reason about certain types of errors for you prior to execution. in dynamic languages, the type information may well be there, but you need to exercise the code at runtime (via tests or whatever, but still runtime) to make use of it.

True, but code is running. If it's not used, then the error won't be relevant anyway. I'm not talking about rocket, aircraft, power plant software. But even there, I never heard that any of those really critical domains use Haskell (or similar) in their control systems.