I imagine another large factor is economies of scale.
e.g. if a machine that makes 1000 widgets an hour is only 10 times the price of one that makes 10 widgets an hour, then you'll get centralisation.
The other factor I imagine is proximity/availability of raw resources, and refineries of raw resources: if you're not shipping those shoes across the world, you still have to transport the plastic, leather, rubber etc to make them.
The other factor I imagine is proximity/availability of raw resources, and refineries of raw resources: if you're not shipping those shoes across the world, you still have to transport the plastic, leather, rubber etc to make them.