For students: The syllabus is to the course you are taking what the instruction book is to a video game, or the manual is to your driving test. Of course, in our day and age, many are used to situations in which you can just learn by doing and consult the instructions if and when you find you can’t figure it out yourself inductively. But until such time as you are taking a course that mirrors that approach, and lets you fail over and over again in the process of learning without it potentially making it impossible for you to pass the class, just start by reading the syllabus.
For faculty: How do you approach this issue of students not reading the syllabus? One way is to follow up with a quiz about it. But it seems odd to me to test students on their knowledge of course rules, as opposed to quizzing them on material that the syllabus told them to cover. I’d prefer to give them a syllabus which tells them to come prepared to do something on the second day of class, and then give credit to those who actually did so, as a better way of conveying the importance of the syllabus from the start of the semester. Another approach would be to include an opportunity for extra credit somewhere buried in the details of the syllabus, and thus available only for those who took the time to read it.
Ultimately, the syllabus is important information about a course. We should not, in my opinion, do anything to help students understand the importance of following directions, other than telling them to and then allowing them to suffer the consequences if they fail to do so. Any other approach will convey that it is we rather than they who are responsible for their education and their overall success or failure.