Under what circumstances is it beneficial for an advisor to seek sole authorship when their advisees deserve to be listed as co-authors? I have seen several questions on this site which suggest that there are (presumably and hopefully rare) occasions where an advisor seeks to publish work as the sole author on a collaborative project that they are working on with their advisees. 

Some questions which highlight these occurrences:


My advisor submitted a paper with my work without including me as an author
what do you do if your PhD advisor publishes a solo paper on your topic?


While there has been some discussion on this site (e.g., here) about whether the advisor should be listed as a co-author on a student's paper, in my field (in the U.S.), it is common for the advisor to be listed as a co-author on their student's papers. So, I'm writing this question to come to some understanding of the "opposite" problem:


  When it (rarely) occurs, what are the benefits for an advisor to seek sole authorship when their advisees deserve to be listed as co-authors?


In my (admittedly naive) view, it would seem that the advisor would benefit more from co-authoring papers with their advisees than trying to pass the work off as their own, if nothing more than to show (to, e.g., tenure/promotion committees) that they are actively engaging their student researchers in the research activities of the group. Perhaps an element of "ego trip" is involved here as well, but I wonder if I'm missing something more fundamental as to why this happens on those rare occasions.



Edited to add — I certainly do appreciate that there is variability in the ways that different departments/institutions in different parts of the world do things, and am attempting to gain some understanding about the not-so-obvious (from my perspective) motivators that lead an advisor down the road to the aforementioned behavior.
In my (admittedly naive) view, it would seem that the advisor would benefit more from co-authoring papers with their advisees than trying to pass the work off as their own, if nothing more than to show (to, e.g., tenure/promotion committees) that they are actively engaging their student researchers in the research activities of the group.


I tend to agree with your sentiment here. The problem is that not every evaluation committee (for tenure, for promotion, for regular end-of-the-year raises) is that sane.

Example 1: in my old university, we had for some time a hard tenure rule that required applicants to have a small number of recent single-authored papers. In applied computer science, basically nobody writes single-authored papers. It is simply not done. I don't know any concrete cases, but I would not be surprised if that rule led to some "single-authored" papers where the work was really done by a master student.

Example 2: I have heard of universities in Asia that base end-of-the-year raises on accepted papers. The concrete amount is dependent on the number of authors, as well as on the place in the author list, making it very attractive to "forget" authors or put the supervisor's name first.

Here on academics.SE, we tend to forget that academia varies more than we think, and just because a certain unethical behavior would not make sense in our university, there is no reason to believe that this is true everywhere.