Ultimately all those signals go over telephone poles or in underground cable. May I remind you that at one time, every competing railroad ran their own track. This became unsustainable when you had eight parallel rail lines, of different gauges, that didn't intersect.

Like rail track, many countries standardized telecommunication wires, poles, etc. They may have still been owned by Bellsouth, ATT, Telefonica, whoever .. but regulations meant everyone had to play by the same rules; allowing competition to buy virtual dedicated circuits on public utility infrastructure.