I think it really depends on your major. In Business studies and Germany this is absolutely the case. Mannheim, St. Gallen, Milano, TUM.

In CS in Germany this is not the case. There are better or worser schools but it is not a big thing. More important, github profiles, experience etc.

For the Politicians I dont see a common pattern. There are diversity issues (rather male, mostly Lawyers or Political Scientist) but German politicians are quiet diverse by background. Example by chancellors Scholz: Rather worser law university Merkel: Good, but not best Eastern Germany University in physics. Schröder: From a very poor family, but rather good law university.

Except Bucerius law school I am not aware of any university with lots of politicians aspirants. (And Bucerius is not that big)

You see I was very bored for doing research.