I tutor math, and one teacher grades honors Algebra II in a very fancy area on a C curve, so the average grade is a C. That is done in many math, science and engineering classes in high school, but I hadn’t heard of it in high school.
Many teachers make up their own material in honors math. It is correct math, but not in any book. They seem to particularly like problems with complex numbers.
All this provides business for math tutors, but it seems a little over the top.