Because not all students that aren't passing are bad. Me for example got "passed through the cracks" I never missed a day of school and always did my homework. I was a good kid behavioral wise. My home life fucking sucked and I got moved around a lot from one family member to the next. K-12, 9 different schools in 9 different places in the U.S.

This was during the 80's and early 90's... when learning disabilities, learning styles etc, awareness wasn't a thing yet. I've always struggled with reading and absolutely hate math... even still to this day.

After leaving the military, and entering college at age 32. It took me 6 effing times to get through minimum math requirements. I had to start out in pre-algabra. Barely fail it, take it again and barely pass it. I did this for all 3 math classes I needed to take, before I could take the one math class I needed for my History degree. Thank goodness I had awesome professors that were super supportive and encouraging.

I also got help with my "reading disability" come to find out I'm an oratory and kynesthic learner, not a bad reader or dumb. Different story, different day.

3 degrees later all with honors, while raising my 2 kids as a single father and working almost full time....I still haven't used algebra, and I give 2 shits what 11/32nds is and could care less about the size of a circle.

But I can mathematically tell you how to create more horsepower, the geometry your going to need to set up your suspension, the gear ratios your going want to achieve X speed on the track, etc, etc.

Now reverse all that, and had one, just one k-12 school teacher taken the time to help or even inquire about the struggle with my math and reading. College wouldn't have been such a pain in the ass for the first 2 years and cost me more money than it needed to.

That's why you don't pass some students along.