I’ve done casual empirical research on how many students actually read the syllabus enough to notice details. The number sometimes creeps as high as 50% in upper-level classes (experienced students dedicated to the subject are more likely to invest the energy, I suppose), but it’s generally closer to 20%.
I could blame and berate the students, but ultimately I just have to acknowledge that a syllabus along is just not a very effective way to communicate. Like it or not, it’s a fact.