As David noted, we updated all the URL parsing functions to be polymorphic back in 3.2: https://docs.python.org/3/library/urllib.parse.html#parsing-ascii-encoded-bytes

We left the quoting functions alone, because they already had their own way of dealing with the bytes-vs-str distinction (quote_from_bytes, unquote_to_bytes, etc) that meant the polymorphic approach we adopted for the parsing functions didn't make sense.

That said, I think it would be reasonable to enhance unquote() to accept a bytes object, processing it as follows:

    unquote_to_bytes(string).decode(encoding, errors)