How much of an onus is on the teacher in an undergraduate course?
I do not think you can solve this problem alone. As such I would suggest collaborating with the teachers who teach the prerequisites to your courses. Knowing what is happening in colleagues classes can help you to know what the students needs our in addition to the governmental requirements.
By working together you can determine how much review and overlap should be a part of each course as students move from one course to the next.
This kind of joint cooperation is common at the k12 level where there is often a similarly centralized control curriculum that ignores the unique characteristics of students.