Why don’t Belgian universities use the same Physics manuals?

Answer

It is not the case that other books also deal with other theories. For example, whether you use Alonso and Finn, or Resnick and Halliday, (titles from when I was in 1st year math myself) or some other typical basic physics book, it won’t matter. The matter covered is the same. It is the teacher’s choice to prefer a particular book, or a few books. Many teachers write their own course, and also recommend books, not to buy directly but to consult in the library. After all, it is often extremely useful to see the same concept explained by someone else. A private course also offers great flexibility to the teacher and costs significantly less to the student. For example, the “Feynman lectures” are incredibly good in terms of explanation, but they were a bit too ambitious for my student-like finances… So definitely go and have a look in the university library and consult various works.

So, different books of physics do deal with the same matter in the end, and they probably do for all the exact and applied sciences. Overall, the physics students at the various universities will have largely received the same theories. Specialization will occur in the master’s years, but even there the specializations do not compete with each other, but offer the university the opportunity to set its own accents and the student to make his own choice.

To what extent this answer also applies to the humanities, I cannot say. I can imagine that, in pedagogy for example, there could be a greater diversity of theories, points of view and points of view than in the exact sciences, without this detracting from the value of those points of view. Also with books about literature I can imagine that the personal vision of the author can lead to greater diversity.
Such diversity should therefore not be seen as a competition but as an enrichment.