are professors held to any standards as far as being consistent with their grading practices for students?

My Math professor is not grading equally for everyone.

after the first exam he did not curve it because 2 people got 100's. But he did allow anyone who got a D or who had failed the 1st test to take the test home, bring it back in a week later with the mistakes corrected, and he said he would add "up to 10 points" to their grade to boost their score up a bit.

My problem with him is that it turns out he lied to the class because i know that he added 30 points to my classmate's grade. she showed me her paper when he gave it back to her. She originally had a 67, now she has a 97 which is 2 points higher than i scored & one of the highest grades in the class. she went from a D to an A+. and last time i checked 67 + 10 isn't = 97, so where iare the other 20 points coming from???

Another thing that really bugs me is that most of the class couldn't bring their grade up even 1 point. Only the failures & D students got the opportunity. I feel so bad for everyone in between. Another acquaintance in class got a low C and wasn't allowed to get any extra points, she is stuck with her grade. He absolutely refused to let her do any extra credit or re-do any of her mistakes on the test. She would have been better off failing it, probably would have ended up with an A!

Now, I am not against letting people do extra credit or have some way to boost a low grade. I've been there most my life & i know the course isn't easy. I think he should allow it, but it shouldn't be only for select people. and I feel like 30 points is excessive. I think 10 points is reasonable. but you can't just be handed an A after getting a D, that is craziness!!! It's offensive to me, i worked so hard to get my grade. she bombed the test now is ranked higher in the class than me. I also think it was unfair for him to cut off the people that scored over a 70 and not afford them the opportunity to boost their grade. Why does he refuse to let anyone who has a low C get a higher grade? it's not like a low C is good, those people could have used a few points too.

I know, I have an A so i shouldn't care right? But i do. It's the principal of it. And it could affect me later. What if on the next test i get a C and am stuck with it but she fails and ends up with an A again? She could be at the top of the class in the end after nearly failing every exam.

My gut is telling me this is wrong and it's been nagging at me for days. Has anyone encountered a professor grading like this, and is there anything that can be done or can he really do whatever he wants? are we at his crazy mercy? please help.....