"Margrethe Vestager, the EU commissioner in charge of competition, said Luxembourg’s “illegal tax advantages to Amazon” had allowed almost three-quarters of the company’s profits to go untaxed, allowing it to pay four times less tax than local rivals."
The fact that they're not so neatly distinguishable is very much at the heart of the problem. One of the main ways companies avoid tax is by making it appear that their revenue, profits, and (to a lesser extent) costs are somewhere other than where they really are. Amazon in the US is very much aware of the tax implications of hiring or locating assets in the EU, whether legitimately or as a pure dodge, and depends on the difference.
https://www.theguardian.com/technology/2017/oct/04/amazon-eu...