You have it all backwards. "Data" isn't a thing that somehow has a natural location-dependent cost. The cost for a mobile provider is infrastructure. They have

You have it all backwards. "Data" isn't a thing that somehow has a natural location-dependent cost. The cost for a mobile provider is infrastructure. They have to buy devices, install them somewhere, and supply them with energy. None of those is in any way inherently much more expensive in the US than in other developed countries. It's only the price that you pay that is expensive, and the reason for that is zero-rating.