I am European: our wages are much, much lower than our American tech counterparts, without taxes double, with taxes we're on average making a third of them. And that's same cost of living.
Copenhagen is probably one of the most expensive city in Europe and hardly representative of the continent as a whole. Even then, a quick Google search estimates that cost of live in Copenhagen is 15-25% lower than Seattle/LA, without even accounting for the absurd american healthcare costs.