Scientists plan huge European AI hub to compete with US
I believe that a contributing factor to the pay gap in Europe is the fact that we have so many languages, that we are too segregated to create the same level of competitiveness as seen in the US.
This means that each country is fairly protective of its people, and even though EU has free movement of labour, the language and culture barrier is strong, and internationals have a harder time to get hired, unless the speak the local language.So the end results is that talent is spread across, and no single country has ability to become the place to be.