Well it's not completely unavoidable, because both my schools did it, and people do graduate from them. Including engineering.
I mean, I was in nursing school. The classes weren't exactly easy. It's not like I was in English 111 wanting a curve. A 60 in classes like pharmacology, organic chem, and microbiology is also normal (or high, actually). We had quite a few tests where the entire class failed. No curve. Just, "Well, you're not going to go work in a hospital without learning this material. So work harder."
My microbiology class, only 2 of us got higher than a C. No one got an A. Out of 39 people, only 11 passed (I'm including D as passing, even though they had to retake it), and only 7 moved on in the program (the 7 of us that got higher than a D). She still has a job, and no one says anything except, "Yeah. That class is tough. You kind of have to devote your life to it."
Obviously it was a small school, so there weren't 500 kids taking the class. But they would have let us all fail if we had failed.
I guess I just don't understand it because I've never had a grade curved in my life. I'm just a believer in: If you don't know this stuff, then you can't have an A. An A implies that you know this material and are ready for more, and that is not the case if you got a 57 on this test. (regardless of whether it's the teacher's fault or the student's, the point is, you don't know the material.)
Like I said, I genuinely didn't even know there were still schools that curved grades.