As a non-mathematician, I am somewhat mystified by the prevailing norms of the mathematics community as I understand them from this thread. Correct me if I'm wrong, but it sounds like:
Supervisors make important intellectual contributions to the thesis work of their students.
Typically, the name of the supervisor does not appear on the work.
For example, the most upvoted comment at the moment says "as a rule the supervisor should not be a co-author in the main paper taken from a student's thesis, even if he has contributed substantially to it." (emphasis is mine) Other comments echo the sentiment.
This seems problematic, both morally and practically. In other scientific communities, the author list is supposed to reflect the people who contributed intellectually to the paper. Manipulating it is an ethical offense. For example, the practices described in this thread appear to violate IEEE policies on authorship which state (Section 8.2.1)
Authorship and co-authorship should be based on a substantial intellectual contribution ... the list of authors on an article serves multiple purposes; it indicates who is responsible for the work and to whom questions regarding the work should be addressed.
Finally, I would just like to add that as a student, I would feel horrible submitting a paper authored only by me if the paper was based in large part on the insights of someone else.