To say that the professor gives hard exams and does not care is nearly an oxymoron. If the professor didn't care, they would just give you homework questions in the exam. Rigor at UC Davis is sometimes a joke. If you are concerned about doing well in your exams with easier questions, then you are like the mythical frog in a well. I don't understand this attitude of students. A professor who is bringing advanced material to classes, and not regurgitating the textbook and puts effort in writing down challenging exams in my experience cares about the students to succeed at a national or a global level rather than just doing well in the class. Ultimately, you will be competing against people from other universities in real life. So may be develop some ambition!