<i>it&#x27;s quite rare that I&#x27;ve encountered a type error in a Python program</i><p>I hear that relatively frequently from people who consider types to be things like functions, strings, integers, and other &quot;representation types&quot;.  But the benefit of type systems, especially type systems as expressive as Haskell, is that you, many times, can encode your logical invariants in the type system by introducing new nominal types.  For example, you can introduce a new type for each type of ID in your system, like CustomerID, ExperimentID, EventID, which prevents you from mixing those up.  You can use types to distinguish between mutable and immutable data structures.  It&#x27;s perfectly okay to use object identity when comparing immutable data structures, but it&#x27;s usually a bug if the data structure is mutable.<p>When you take a more expansive view of what type systems can offer, they&#x27;re more useful.