The issue is Facebook Ireland or Apple Sales International are separate entities from Apple or Facebook US so on paper the profits are happening in completely d

The issue is Facebook Ireland or Apple Sales International are separate entities from Apple or Facebook US so on paper the profits are happening in completely different companies like Honda buying a car part from another company. So how do you effectively tax that just by saying we also tax overseas profits as well. To do that we'd have to define and pierce all sorts of corporate veils about true owners, decide what the threshold is for being legitimately a separate business and not just an international subsidiary.