Good question, I think this depends on the educational institution to which the researcher belongs, so that the universities of the Third World depend on the sequence of researchers and give points according to priority. We do not agree with such a system.
There is a general rule in arranging the names of authors in a publication. In Brazil, in general, the first corresponds to the main author, being able to be a undergraduate student, master student or doctoral student. The last one corresponds to the supervisor of the student. The other authors correspond to the participants of the article who brought some collaboration. If all authors are professionals, the first name usually refers to the person in charge of the work or coordinator of the research. Therefore, each country as well as educational institutions may have their conventions or rules for publications.
The order of researcher shows the contributions given by each author. It must be followed in true sense. But few supervisors always like to have their names at first place that may be because of their dominance in that particular area of research. However, it all depends on the consent and understandings among the researchers. Overall it should not lead to conflict of interests.
The first or lead author is the one whose contribution to the research is the most significant. That position is occupied by students with their supervisors' names following in succession. It is ethically wrong for supervisors to take the first authorship slot when their students have done all the entire project with them playing the role as 'guardians'.
There are some cases where undeserving members of the department are hooked artificially as co-authors in the research papers of students though they never played any role in the carrying out of the research. Being an author means you are responsible and played a significant role in the unfolding and final execution of the research and it's writing. 'Lazy' faculty members don't deserve any authorship rights. Universities must have strong ethical laws regarding publication of students' research papers as some students are coerced to put artificial names on their papers. Shame unto such low-profiled 'scholars' who engage in this scrupulous 'academic/authorship theft'.
I think each university has a specific guidelines and format for designing dissertations and thesis. So the order of name would also be part of the guide.
The order of name on a research paper is important because it shows the degree of contribution to the work in descending order, it is unprofessional for a senior researcher to force a junior one to put the senior's name first. For promotion purposes, higher points are awarded to the first author followed by the second and so on in my Institution. The last author gets the lowest points.