Well think about it this way... Why don't professors use the same standards about missing classes/using it as apart of your grade across the campus.
I can miss as many classes as I want for my chem stuff, you just can't make it up anything missed, but with my math class, miss more than 2 classes your attedance
grade
is now a B+.
And my Math prof wasn't joking when he said if the entire class gets all A's that he'd get a raise.
And the grading scale varies greatly too. My chem class anything from a 90-100 percent is an A.
I've had an English prof that based your entire grade for the semester on three pieces of work. And even there, it was hard pressed to get an A. No point system there.
And my Biology class last semester had the tradition 90-93% is an A- 94-100 is an A.
Same campus, same college, yet there is no consistency.