Barnard has 2,300 students while USC has 43,000. Barnard has higher endowment per student but is far more desperate for students to attend their 4 acre campus (Yes, I was surprised when I read that as well - that’s like a quarter of the size of the USC village). Clearly, they have lower operating expenses, and I wouldn’t be surprised if they had to distribute aid across a far smaller percentage of students than USC. If you were to compare income statements, Barnard would be expending less than 5% the money USC does on Financial Aid, which is presently $460 million.
24% of USC undergraduates are pell grant recipients, and most of them attend USC for pennies. I am one.