You are all mediocre
I wonder how long I would have my job if at the beginning of the year I tell all my students:
"I have this wonderful new rubric I will be using to evaluate your work and help you improve your learning skills. I am going to assume that all of you are mediocre students, so the most you will be able to score on any assignment is 75. Now, work hard for 9 hours a day, volunteer for extra work after school, and spend hours of your own time providing gobs of evidence that you are doing this. Prove to me that you are a good student. Now, let’s not worry about this rubric. Relax, and have a great year.
P.S. Even if you do all of the above, and even if I decide to give you a higher score, it doesn't mean you will be considered any better than your mediocre classmates or receive any higher compensation. Your reward will be even more responsibility and knowing you did your very best."