That part is a plug (male part) not a jack (female part). It gets plugged into a jack. Eg. (From Digikey):
This kind of plug part is not designed for small quantity use- the wires will be welded (not soldered) to the plug. It is a much faster process and the joint strength is greater without taking so much space up.
Following that, the plug body and strain relief is insert-molded onto the cable/plug combo using a low-pressure PVC vertical injection molding process.
See this video for the process.
Above you can see the girl loading the cable assemblies into a mold while another mold is filling and cooling. When the cycle finishes the second mold rotates into place and the operator goes to work filling the first mold.