Do German universities consider high school grades? Do German universities consider the high school grades for post-graduate admissions since they ask for it?
In theory there is no way to prevent them from doing so, but in general they will focus on more relevant things like bachelors degree.
The reason they ask (apart from the German love for bureaucracy) I believe is a weird quirk in German law. In order to study at a German university you need a &quot;Hochschulreife&quot;, i.e. the qualification for university studies. This is normally gained by finishing high school.¹ It is however not gained by having a university degree, even though it is technically needed to get one in the first place. So in order to gain admission into a masters program, you both need to prove that you have the prerequisite bachelors degree, as well as the general qualification to study (i.e. have finished high school).
¹The specifics are a bit complicated, as not every type of German high-school counts. For foreign systems, I believe there are endless lists of what is equivalent and what is not, but in general this is not a high hurdle.