The parents escalate to the adminstrators, who either involve the student counsellors or talk to the teacher directly. One of these two tell the teacher how they need to better support the student because they need a "little extra help" or can't handle the stress required to turn in homework assignments.
I wish this stuff worked, but these parents typically don't want an answer that requires their student to work harder (or differently). They want the curriculum, assignments, or grading scheme to change until their child gets an A - and they don't care about mastery.
Now, if even the administrators can't do that then someone in the city government, state government or federal government should be able to draw the fundamental line whether the purpose of schools is to give students A's or grade them based on their actual knowledge and make the student responsible for his/her own grades.
This is one of the big advantages of national standardised testing. There is literally nothing the school can do to alter the grade.
And stop at that.
Otherwise you start on a losing discussion.
So all in all, students who ask for that end up with better grades and better chances where grades matter.
By indicating a personal and subjective intent to be ungenerous, parents will feel (perhaps rightly) that they want to take this further.
Edited to add, my approach would be more like:
"I have graded 8bitsrule as generously as I could under the circumstances, and the grade is final. 8bitsrule will need to show a better understanding of communicating diplomatically in order to succeed in next semester's courses. 8bitsrule could try the following specific tasks over the break:"
But if everyone graduates and gets a honors degree, the only thing that degree means is that you were able to get in (either through skill or money).
I’m sure it still has value. But it places all the value at the entrance and selection process instead of the teaching.
This is an interesting interview about it: http://www.econtalk.org/bryan-caplan-on-the-case-against-edu...
https://www.quora.com/Is-Harvard-the-only-university-where-9...
"She can't, because that's the grade she earned in the time alloted. The moving finger, having writ, has moved on.
"However, I'm confident that, with Janie's capabilities, a little more effort from her and help from you, she can easily demonstrate a higher level of mastery and the consequent benefits from longer-term retention.
"Princeton will NOT be a picnic, and developing excellent habits at this time will pay back many-fold. This A- is a vote of confidence that there is room and talent for improvement."