I think it’s a supply/demand problem of qualified teachers in math/science. In my NJ district of above average kiddos, the honors/AP math/physical science courses are extremely difficult. This ensures that the number of Ap Calc BC and AP Chem/Ap physics sections stay small. And did I mention that the math and science teachers are available for private tutoring during the spring/summer to prepare interested child for the very difficult courses?
No such issues for language , history honors/AP. They are rigorous, but are not known for successive filtering like the math /science courses.