The percentage facilitates students' understanding of their school performance. This is because using percentage as a grading system makes it easier for students to translate percentages into letter grades, so it is easier for students to evaluate how well their academic performance is and what areas need to be improved to improve their grades. In addition, it facilitates students to direct their efforts to achieve the required grade for a specific course or university.
Poverty plays a controversial role in U.S as some politicians would increase or cut taxes on benefits/aids for others. I know it’s not that much but hope this helps