First, they don't act like that, and if they do that's dumb.
Second, how is that different from writing in a statically-typed language like Haskell/Rust/what have you and then compiling down to assembly which is for all intents and purposes dynamically typed? We do it hoping to gain safety from the typing, but do we lose the type safety in the machine code? (We don't, the type-safe language rules out compiling to certain classes of erroneous code.)