Ooh, rant time.
At least at my school, the administration is stupid as hell and will jump down a professor's throat if the class doesn't have exactly the sort of grade distribution they want. We also have a policy that 90+ is always at least an A, 80+ is at least a B, and the professor can lower those cutoffs if they want, but not raise them.
If you're a shitty professor and your entire class is failing, this is fine; you just curve the class up and fly under the admin's radar.
If you're a good professor though, and your class is doing way better than other classes have done with different professors, prepare to enter fucking administrative hellworld.
The professor I work for taught my thermo class and was easily one of the best ones I've ever had. Our tests averages were in like the 80s and I actually understood everything. Meanwhile, some other dickhead professor taught another section of the course and was getting averages in like the 40s and 50s, despite the tests being nearly identical to ours, if not easier.
He could just curve his class up though. Admins never gave him any shit.
Meanwhile, my profesor has been losing her goddamn mind trying to get the admins to realize that her students are doing better than his and that she shouldn't be punished for teaching too well. Apparently, they want her to be failing 20% of her students, which she finds absolutely unacceptable.
Other good professors I've had have just had to resort to shitty dumb tactics to get around this. One will put a basically impossible challenge question at the end of his (otherwise well written) tests to drop everyone's score by 10%. One just grades like a fucking animal and something as minor as a sign error or algebra mistake will lose you 10%. It's very difficult for them to fine tune it to what that admins want to see, but if they've accidentally overdone it, they can curve the class back up.
The gist of it is that professors are actively encouraged to just tank their class grades and then curve them up to what the admins want to see. It's by far a professor's easiest path.