Shoot, I hope all med schools have a passing rate of 70% on every course. I'd hate to see a school that fails 30% of its students.
Oh, I misunderstood your post. No, each school has different standards, and every class (for us) is different. For example, most classes are 70%, and some classes it is up to the professor and may be set lower if our class is "particularly dim" this year.
A pass score of 70% does not mean that 30% of the student fail. This is the minimum that you must achieve in order to get a pass on each exam. Most medical schools have less than 1% of students who fail and most fail because they are not able to put in the time required to master the material. It's all about volume in medical school and some folks will gamble with easing up on one or two courses to put their emphasis on the bigger courses.
Most courses in medical school are scaled around a class mean too which tends to help those that score a bit lower but lower the higher scores too. USMLE and all specialty board exams will grade in the same manner so get used to it.