Does it make sense to make exam grading very transparent? Is it advisable (in terms of the benefit for the students and the work it causes) to make the grading completely transparent to students? I think for instance of publishing the sample solutions for the exam or the distribution of the grades given. Would those measures be suitable to convince the students that the grading is fair or would it rather make worse students feel treated in an unfair way and trigger many complaints? As far as I understand the University now normally lets the students only see their individual grades. Of course they will always compare themselves in smaller groups.
Transparency is great, when you can do it.  Many of my large undergraduate classes would show a score histogram for every major quiz or exam, and some would explicitly give the grading rubric.  This was generally very much appreciated by the students for exactly the reasons you give: better understanding of how they stand and why they got the scores they got, letting them judge fairness and know when to reasonably object (which sometimes happened).

From the TA side, my experience was that transparency actually decreased my work, because it meant that I didn't need to deal with many spurious complaints, and that many of the complaints could be resolved directly through reference to the rubric.