I suspect these fixers were left out simply because no one expected anyone to call the dunder names directly; the whole point of the dunder names is that they're not used directly, being invoked by syntax/context (__nonzero__ being the first thing tried for implicit boolean testing or calls to bool/operator.truth) or by top-level functions (__oct__/__hex__ being called by oct/hex).

The only legitimate use case I can think of off-hand would be in class hierarchies, where a child dunder method is implemented in terms of a super() call to invoke the parent.

Do you have any examples of code bases that rely on this? I've never seen one personally, but I'm not about to claim exhaustive knowledge of all Python code in the world.