When you want to study Psychology in Germany, there is currently a numerus clausus of 1.3 (with 1 being the best mark and 6 being the worst). That means that only the best few percent of high school students are admitted to study Psychology (marks are approximately normally distributed between 1 and 4). We have tested the intelligence of our psychology students and found that it ranges from around 100 to around 140, with the majority scoring around 110 to 120. In fact their distribution looks like a 100 to 140 segment of the intelligence bell curve, with only a very few students scoring more than 130. This means that despite them being the top ranking students by school graduation marks, they don't rank among the top intelligent of the population!
Now, if you remember that intelligence is defined as general cognitive problem-solving skill, you cannot be surprised that at least for students of Psychology their problem-solving skills are only mildly above average. That they are not much interested in performing in a field they don't excel at, is not surprising.
With our students, I see the same thing you see with yours. Only a small number of people have this personality trait to an extent that they will excel in any academic discipline. The majority of students are in fact cull: they happen like sawdust. Which is a problem of bad admission selection based on irrelevant characteristics like school marks and memory capacity, which causes good marks in test like the GMAT or high school graduation, but not new ideas in research.
Basically and to sum up, my answer would be: Most students are too stupid to solve problems and are only at a university because better admission selection would cost too much money and because a harsher selection contradicts the current ideology of equality.