I don’t think it covers the situation to say that the schools will pay the exam fees for students whose families are unable to pay, if that is based on free or reduced lunch status.
There was a survey fairly recently that asked people if they could come up with $400 in case of an emergency. A very high proportion of the people surveyed said it would be difficult (well beyond the fraction who qualify for free and reduced lunch, I would guess)…
I can easily understand being uncomfortable with paying $658 to CB (on top of everything else that has been paid to CB) for AP exams that will not grant any college credit, even if the family has the money with no trouble and did not have any other planned use for it. An obligation to do this, in order for the student to receive credit for the class (or to receive the AP grade bump), seems like an inappropriate demand by the school.
In our case, to come up with $658, Rover would have to do without the Orvis Super-Comfort dog bed with the Tempur-pedic filling and the special chew-resistant fabric cover. (Rover keeps giving me sidelong glances.)