So why is the issue you described an issue? Because it's about a grade. And the reason that's relevant is because that credential will then be used to determine where she can to to university which, in turn, is a credential that will determine her breadth of options for starting her career, and so on. But why is this all done by credentials instead of simple demonstrations of skill? What somebody scored in a high school writing class should matter far less than the output somebody is capable of producing when given a prompt and an hour in a closed setting. This is how you used to apply to colleges. Here [1], for instance, is Harvard's exam from 1869. If you pass it, you're in. Simple as that.
Obviously this creates a problem of institutions starting to 'teach the test', but with sufficiently broad testing I don't see this as a problem. If a writing class can teach somebody to write a compelling essay based on an arbitrary prompt, then that was simply a good writing class! As an aside this would also add a major selling point to all of the top universities that offer free educational courses online. Right now I think 'normal' people are mostly disinterested in those because of the lack of widely accepted credentials, which is just so backwards - people are actively seeking to maximize credentials over maximizing learning.
This is one of the very few places I think big tech in the US has done a great job. Coding interviews can be justifiably critiqued in many ways, but it's still a much better system than raw credentialization.
[1] - https://graphics8.nytimes.com/packages/pdf/education/harvard...