You do not understand. Of course a 4.0 is a 4.0. But you have to realize that schools are not stupid. They know which schools are not so easy and which ones are. Which ones are harder and which ones are easier.
Let me explain, I know several people who could easily get a 4.0 at USF based on the fact that grading scales are so lenient, sometimes use of old tests and taking online classes that are a joke. Yet, a very high percentage of these people to actually get a 30+ MCAT is a lot lot lot smaller. In fact a lot of people close to 4.0 at my school werre getting 17s and 18s and 19s on the MCAT. Not to say it was everyone.
On the other hand, schools like more competitive schools in state and out of state are more difficult, they may require you to really think about the questions rather then just memorize, may not have easy A online classes, etc., so you really have to work for the As and furthermore, they don't let anyone and everyone into their university but expect higher standards in standardized testing. So you look at a school that will have higher selectivity and also challenge their kids more and youwill see that their MCAT scores and other things are higher.
Also, 2 professors within a given school could be so totally different. One could make the scale a rather tough scale and make their tests more challenging while another makes it a joke. This has been true at USF.
Therefore, you cannot say someone with a 4.0 from one school or even one class is equal to a 4.0 in the strict sense. Also some majors are truly easy whle some like engineering are truly difficult.
On the other hand, MCAT scores are equalizing across the board because they are standardized and normalized. This is why the MCAT in some ways is more important then GPA. But GPA is a lot harder to repair then an MCAT if you mess up. However if you have a low GPA but above the min. with a high upper trend or SMP and a high MCAT you will most likely get a chance. Whereas if you get a High GPA and a low MCAT and can't bring that MCAT up any, you will be screwed and kept out.
Why do you think all this is? Because GPA is not standardized across the board. Also, some schools will use one kinda scale i.e. +/- scale, some will not, some will call A a 85, some will call an A 90, and some will call a regular A a 94 and above.
You see my point?? That's what I mean by GPA is not equal. you will understand when you enter college.