Why multiple wires for same voltage?

EPaul; from a mechanical/manufacturing standpoint:

Multiple small wires may be more practical to attach to printed circuit boards and connectors than large gauge wire.

The connection of several small wires may be more reliable than a single larger gauge wire.

Small wires are more flexible than a single large conductor.

It is less costly to purchase and stock a zillion feet of small wire than many different gauges of wire.

Too, in some instances, multiple small conductors have electrical characteristics that are

somewhat different from those of a single larger conductor. The difference may be significant

and advantageous from an electrical standpoint.

In a computer power supply, minimized manufacturing cost and maximized reliablility

are probably the reason for multiple wires for the same voltage.

Everything I know is wrong.