This general observation does also apply to performance issues. I can’t speak for any other service, but I know from personal experience that in CERTAIN US Army courses the instructors were given explicit direction that some foreign student or another would not, under any circumstances, fail the course. The direction after that was to keep this in mind and “simply do your best” with regard to trying to get the most from that student.
Even in the Ranger course, I was told in no uncertain terms by my RI TAC that my foreign student “Ranger Buddy” was going to pass the course, and it was MY job (as his “Ranger Buddy”) to carry him through all the events. His patrol scores would be MY scores and vice versa. I was not the only student in that class to get such direction. (All of the SF students were assigned foreign students as “Ranger Buddies” and told the same thing by the various RI TACs.) Needless to say, ALL of the foreign students passed and graduated in our class.
As an instructor in SF Phase III, I was given direction by my RL Team Leader that I was to “informally counsel and provide mock grades” to my foreign students while ensuring that their “formal written grades” always reflected a passing score (even if it was a minimum passing score). The stories I could tell you… LOL!
To be sure, not all of the foreign students needed (or even wanted) this “special treatment,” but if they had “performance” or “attitude” issues, this is how the problem was handled on many, many occasions. I should also note that I had more than one US Army SF reserve or NG student that also got the “foreign student” treatment depending on his civilian circumstances (usually political appointees or professional / senior federal or state bureaucrats).