You don’t understand social mobility, it does not imply what you think it does. It primarily reflects the smallness of a country and wage compression. Countries that are neither small nor have wage compression, such as the US, will always show poorly by that metric.

You can, in absolute terms, dramatically increase your income in a country like the US and still be less “socially mobile” than a small income increase in a poorer country. People care about dramatically increasing their income much more than they care about being “socially mobile”. If you care about individual prosperity, social mobility is at best a secondary measure of success.

This isn’t a new phenomenon, the EU still struggles to produce genuinely innovative companies.