Indeed. This seems to be the main problem. One running joke around my family / friends is that a hardworking B/C student does best in Engineering majors, because they work hard and are used to getting poor grades anyway. They've already come across that problem in their life.
On the other hand, students who got straight A's throughout high school become surprised at the difficulty, get their first B in their lifetime, and feel bad about themselves... possibly even switching majors.
The first time I came to India, I sucked at their grading system and it broke my bubble of being a precious snowflake who always did well. I think that was a good thing really; it got me used to the idea that grades could go fuck themselves. Much later, when I changed careers and started doing more math here in the U.S., it helped a lot because the whole idea of getting a B+ didn't matter so much. I knew a lot who were in my math classes who were probably smarter than me but dropped out because they couldn't handle the idea of struggling.
I suppose I was fortunate that the time that I started my Mechanical Engineering degree had coincided with a transition to a general "idgaf" attitude about my grades.
I managed to get an "F" in High School History, which was a low point for me frankly, but the C's that came later in Engineering were no big sweat :-).
Focusing on learning, instead of getting decent grades, seems to have been a good thing... definitely contributed to my sanity through college IMO.
On the other hand, students who got straight A's throughout high school become surprised at the difficulty, get their first B in their lifetime, and feel bad about themselves... possibly even switching majors.