Claims that "All strings are made in the same factory!" is utter nonsense. Each type is made in a different locale.
Flat wounds, regardless of manufacturer, are made in a small flat in East Sussex, hence their name.
Similarly, ground wounds are all made on a farm just outside of Punxsutawney, Pennsylvania, by rolling the strings on the ground until sufficiently abraded. Groundhogs are rubbed over the strings and if the fur snags, the strings are ground some more until the fine hairs of the groundhog do not catch.
Hex wounds are made in Haiti by voodoo priests.
Peculiarly, round-wounds have nothing to do with their shape, they're just made in Rwanda and the name over time has become transfigured.
Interesting. What about coated strings? And tapewounds? And gut strings for upright?