Server socket accepts connection without listen

It has always been my understanding that it is essential for a server socket to listen() before it can accept connections.

However, this appears not to be the case.

import socket
import threading
ADDRESS = 'localhost', 10001
EVENT = threading.Event()
def server():
    with socket.create_server(ADDRESS) as _socket:
        #_socket.listen()
        EVENT.set()
        conn, _ = _socket.accept()
        with conn:
            print('Got client connection')
(_server := threading.Thread(target=server)).start()
EVENT.wait()
with socket.socket() as _socket:
    _socket.connect(ADDRESS)
    
_server.join()

Running this gives:

Got client connection

i.e., it worked without a call to listen() on the server socket.

There is no difference in behaviour if I invoke _socket.listen()

Is this something that's peculiar to Python or am I misunderstanding something fundamental?

Python 3.11.3 on MacOS 13.4

create_server is a convenience function. It has a backlog parameter and calls listen for you.

From the docs:

> … backlog is the queue size passed to socket.listen(); if not specified, a default reasonable value is chosen. …