Good point about being failed by other teachers, and sometimes the system in general.
I have had students in my college classes at one state school that have writing skills which appear to be something like a 6th or 7th grade level. The state sponsors a program for students from low-income families who are the first generation in their family to go to college. Some of them make it, some of them don't.
Another student I had went to a school that was so poor it couldn't afford individual books for the students. It was an introductory anatomy and physiology class, and she was clearly a bright girl and was one of the best in class, yet I had to teach her Roman numerals when we did cranial nerves - as she was lost when we started doing using them as nobody every taught those to her... Just an example - there were plenty more like this.
So, sometimes these students get into college unprepared, for many reasons that are beyond their control... Really a tough situation. In some cases the students are lazy and don't care, in some cases the students work hard but just struggle due to lack of background, in some cases they shouldn't be there in the first place - I think all of these contribute to the situation.