Quals are a standard part of graduate school. Many MS-only programs don’t require them, but most PhDs have done them. Quals work great as gatekeepers. But I think they can only work for small cohorts who have already self-selected into a challenging program and fewer students will give into the temptation to cheat (some will still cheat but it’s a lower proportion). Part of the secret sauce toward graduate quals is that most of the time the faculty know who they are going to accept before you even take the test- the test results probably only rarely flip their opinion of their students.

Quals will never be implemented at large in undergraduate mass-market coursework. The need for a placement exam on day one is supposed to be satisfied by prerequisite coursework. The fact that you have to pass a pre-calculus course before starting calculus is enforced by the school. Transfer credit from another school is supposed to be vetted by the registrar. And for the most part it is enforced, but the students still suck. Partly because if you struggled to get a C in pre-calculus then you’re not actually ready for calculus, especially after a couple week break in the summer or winter. Plus, a decent portion of students cheated to pass their pre-calc class. We could easily raise the pre-requisite requirements to a B+ or better, but that won’t actually work. There would be increased pressure to cheat, plus the alumni would stop their donations when their kids are forced to drop out.

The same thing would happen with a qualifying exam on day one. Many kids would cheat, so you’ll still get a bunch of unqualified students in your course. If you somehow managed to keep students from cheating you’d have so many students dropped on lesson two that you would break the school’s course scheduling system every semester. Would those failing students need to take their prerequisite courses again, or should they get to try again on your qualifying exam next semester without any extra courses? Either way is a disaster. The school would absolutely not let this go on for long in any decently sized course.

I don’t know what the answer is. It’s easy to say “just enforce the standards” but if nobody else is doing so then your efforts are wasted and you’ll probably get fired anyway.