Our district does not require the tests to be taken and does not pay for them. However, there is value to taking the tests, even if it does not lead to credits. As others have said, the school’s profile and ranking can be based on number of APs offered, number of tests taken, and the percent of kids doing well. If all the kids going to elite schools opt out of taking the test for 7 APs as seniors, the overall school scores would go down. That may be why the district requires the students to take the test.
Our district also uses the results to make decisions about course offerings and who is allowed to take the tests. Unlike some districts, ours is fairly restrictive on some AP classes which continues the very high percent of kids that pass. Another local district, for example, has kids enroll in a BC calc class but have them take only the AB test.
I would think that if a family has a economic reason for not affording the test, there may be money to pay even if they were not eligible for free lunch. If a family really objects, the school may let the kid out of the tests but that information would get out and other kids would follow.
I don’t think the district should be required to pay for these tests. The students benefit by gaining access to college level courses.
It looks like Williams uses some AP scores, along with other factors, for placement of students in certain departments. A top score on BC calc may get a kid out of one semester of calculus (even if that doesn’t mean they can graduate early).