All of the established domestic car manufacturers have significantly expanded their operations in Berlin in the last 5 years (though mainly R&D, especially software). Germany has relatively high immigration, and it's a lot easier to draw highly qualified immigrants to Berlin than to the Southern German countryside due to the youthful appeal and lower CoL of the city. The US, OTOH, has become more hostile to immigration over time. From a "competition for global talent" PoV, Berlin is a decent stake in the ground in many ways. Tesla also has plans to build an R&D site on the land of the recently shuttered Tegel inner city airport.