Earlier quoted context omitted.
Tbt, I haven't seen that much evidence that correlates developer ability with salary. For example, developers living in the Silicon Valley are paid the most. Not because they are the best, but because they are living in the Silicon Valley. Geographical factors play a much bigger role in compensation than developer ability.
But that 'greater' SV salary for a junior developer can give you less purchasing power than a 'lower' salary for a senior somewhere in Europe, due to cost of living. Granted, money is 'absolute' if you use it to e.g travel around the world, but most people don't do that. In general money is 'relative' to one's environment.
Also, "Europe" means many things. I am talking about Berlin here. I also know other places, like Madrid, where you just simply earn pennies in comparison so the difference becomes even higher (Madrid is more expensive than Berlin, earn less)
I still decided to stay here though (because of quality of living, work culture, music and partying, politics).