There is another randrange() oddity.  If stop is None, the step argument is ignored:

    >>> randrange(100, stop=None, step=10)
    4

If we want to fully harmonize with range(), then randrange() should only accept positional arguments and should not allow None for the stop argument.  That would leave the unoptimized implementation equivalent to:

    def randrange(self, /, *args):
        return self.choice(range(*args))

The actual implementation can retain its fast paths and have a nicer looking signature perhaps using __text_signature__.