> Especially the tax code and measures against people succeeding too much like in America.

This is a big one. Why would someone earning €60k as a regular engineer take all of the responsibility of leading a team for only €10k/year more? Anyone actually qualified for that position knows it's not worth the additional money, and anyone that would accept that promotion is only in it for the title and is likely unqualified. Not to mentioned that you only see half of the additional €10k after tax (in Germany).