I agree that it would be nice to have. But this feature has a cost.

$ ./python -m timeit -s 'from urllib.parse import ParseResult' -- "ParseResult('http', 'User@example.com:Pass@www.python.org:080', '/doc/', '', 'query=yes', 'frag')"
Unpatched: 1.61 usec per loop
Patched:   2.1 usec per loop

$ ./python -m timeit -s 'from urllib.parse import urlparse' -- 'urlparse("http://User@example.com:Pass@www.python.org:080/doc/?query=yes#frag")'

Unpatched: 8.87 usec per loop
Patched:   9.22 usec per loop

Is this cost significant?

The cost can be decreased by using global _tuple_new = tuple.__new__. But this couples the code too tight to implementation details of namedtuple.