That's ridiculous. The cables are harvested by independent contractors who wholesale them on auction at regional fairs. They are then binned into lots by middlemen who on sell to exporters, who on-sell to importers who distribute the cables to distributors. The distributors then supply retail B2B to cabling companies who in turn are subcontracted by the ISP's you mentioned.
That is why natural fibre optic cables are so expensive these days.