Problem being that sets aren't consistently ordered and conversion to a tuple can result in an exponential (specifically, factorial) explosion in the number of possible keys associated with a single set. Nor can you sort all objects. Safe conversion of sets to tuples for use as keys is possible but the only technique I know requires an auxiliary store of objects (mapping objects to the order in which they were first observed), which doesn't parallelize well.

tuple(sorted(s)) and if you can't even sort the values, they're probably not hashable. I get that this involves a copy, but so does frozenset, and you can cross that bridge in various ways if it's ever a problem.

Here are some types that support hashing:

  str
  bytes
  int, float
  complex
  tuple
  frozenset

Aside from int and float, you cannot perform comparisons between objects of different types. Moreover, you cannot sort complex numbers at all.

I have crossed that bridge, and I'm telling you (again) that a sorted tuple is not a generic solution.

I'm not saying the problem with tuple doesn't exist, but that there doesn't need to be a built-in way to deal with it. If for some unfortunate reason you've got a mixed-type set that you also want to use as a dict key, you can write a helper.