That's presumably why so many professors are banding together for this letter. 600 professors is a fairly significant chunk of the faculty.

professors who don't/can't cover their curriculum also get in trouble. if i had to dedicate half of my classes to reteaching things the students are required to know before taking my class, i would not cover what i am supposed to, which then has a knock-on effect to the classes that my class is a prereq for.

whenever i have had a larger-than-normal percent of my students failing, i am provided an opportunity to explain it.

Also these are most likely the first classes. You can not block most of your entering cohort. Or even any way significant part. At least in the system these professors exist in. In some other systems like say German where getting in easy and getting rid of some is normal would be different.

That is the entire problem in a nutshell. You cannot reject more than one or two students in a year or the school will reject you.

This is why universities have offered what amount to remedial math classes for donkey's years. Even in the early 2000's, if you showed up to Calculus I without sufficient preparation, you'd find yourself bounced to Pre-Calculus by the end of the week.

The types of students who are entering college needing dramatic remedial math are not the ones you want to fail in large numbers.

Tenured professors do often fail large swathes of the class, and it's not hard to stand their ground because academic freedom is still very important in universities. This is not generally true for non-tenured and adjunct professors, but for a different reason -- their job review rely on a large part on student feedback forms, and failing students are not happy students.

The idea that if only all professors stood their ground then somehow students will be motivated to study doesn't pan out in practice, though. There is already a significant number of students who are perpetually struggling. They are missing basic prerequisites, and instead of catching up on them, they repeated try and fail at learning the same materials, passing only when they got a lenient instructor. The problem compounds because failing brings helplessness and exacerbates their mental issues, which brings more failing. The university cannot sit on their high ground and watch these students struggle, especially if their number reaches a critical mass.

When I studied in Austria everyone with a high school diploma would be eligible to matriculate at Vienna University of Technology[1], but then the first semester courses would have a bunch of "knock-out" exams that would have a large chunk of first semester students fail and eventually drop out.

IMO this is "fairer" but of course it means you might lose a semester. Helps that there's barely any tuition fees.

[1] Even then (~2005) that wasn't the case for all universities though. Medical university already had entrance exams, mainly due to the high number of German students trying to enroll.

This sounds like the real underlying problem then