Our high school is similar. My kids have gotten 5s on the AP test but Bs in the actual class, and not because they missed class or didn’t turn in homework. The teachers at our HS have very high expectations in honors and AP classes and they grade accordingly. On the plus side, my daughter was very well prepared for college and did not find it to be difficult.
FWIW, my daughter attends a public university. She has been educated, has received individual attention and has had professors and administrators who care. Private universities haven’t cornered the market on that.