I will explain it the way I've experienced it, having had 2 kids go through both private and public schools.
You are most probably in a larger public school. Maybe 2000 plus kids? They have regular classes, honors classes and AP classes (unless they have an IB program. There are a lot more AP schools than IB...)
She is taking regular classes. I'm sorry to say this, but regular classes are not really for college bound students. That doesn't mean that plenty of college bound students don't take SOME regular classes.
Your child does not have to be gifted to take honors or AP classes. However, she has to prove to the teachers and the school that she can handle and do well with honors classes. She needs to be one of the regular class STRIVERS in front of the teacher. She needs to be participating in class. She needs to do her homework consistantly and well, and do well on tests. And she needs to tell the teacher that she wants to take honors courses next year. The teacher will go to the school on her behalf. And she needs to talk to the guidance counselor who helps her sign up for her classes.
Next year, her sophomore year, should be honors year. THEN, as a junior, she should move up to taking 3 AP courses. No more. Only if she makes all A's next year in honors classes should she take 4 AP courses. (Some schools won't allow more than 3...) She'll certainly know what she's doing in AP by the time she's a senior.
If a certain subject is really hard for her, then she can take an honors class in it, rather than AP.
The truth is, the schools HAVE to cater to different levels of ability and performance. You should be glad of that too. If there were only one level, the kids who aren't able to keep up would ALWAYS be behind. The AP classes have lesson plans that move toward AP testing which will determine if they get college credit for the course. The honors is in between. It's really a win/win for everyone.
As far as high performing private schools are concerned, the regular classes are more like honors, IF it's a good school with high quality teachers. Sometimes they don't have the money to pay high quality teachers, and you end up getting lower quality even though you're paying big bucks for private school.
Hope this helps.