Is it tougher for international students to get financial aid in good U.S universities than it is for nationals?
Definitely. For non-US citizens, almost all colleges are need-aware, which means they take your ability to pay into consideration when they are deciding whether to admit you or not. Currently, only 5 colleges are need-blind (do not consider your financial situation when admitting you). They are: Harvard, Yale, Princeton, Amherst, and MIT. So yeah, getting aid as an international student is much tougher.
Why wouldn’t it be? Does your country give equal priority to giving financial aid to foreigners as to its citizens?